CBSE > Class 09 > Science | CBSE Board | Homework Help

Ice is more effective han water at 273 K as it posseses the latent heat of fusion of ice. On turning to liquid ice will absorb this extra amount of heat from substance and cool it in the process.

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A body is moving with the velocity 120km/hr.How much distance Will it cover in 30seconds.

Posted by Nikhil Bhati 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Kulveer Singh 4 years, 4 months ago

What is velocity?

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Fill in the blanks An Element is made up of________

Posted by Tushar Dhaka 4 years, 4 months ago

CBSE > Class 09 > Science

4 answers

Chirag Dahiya 4 years, 4 months ago

Svbsjsiryr45rrrrt6j5ijf

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Avnish Bansal 4 years, 4 months ago

Atoms

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Raj Vishwakarma 4 years, 4 months ago

Atom

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Smriti Garg 4 years, 4 months ago

Atoms or molecules

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Difference between diffusion and osmosis....

Posted by Faiza Tanvir 4 years, 4 months ago

CBSE > Class 09 > Science

2 answers

Kanav Dumra 4 years, 4 months ago

Diffusion occurs in all three states ( solid, liquid, gas ) but osmosis occurs only in liquid particles. Diffusion is a fast process than osmosis. Diffusion makes movement of different particles of different states but osmosis makes the movement of solvent particles only. Diffusion occurs in both directions but osmosis occurs only in one direction.

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Aashi Singh 4 years, 4 months ago

Diffusion is a fast process ans osmosis is a slow process. Diffusion occurs in solid, liquid as well as gas but osmosis occurs only in liquid. Diffusion is the movement of particles of solvent as well as solute in all direction but osmosis is a movement of particle of solvent in one direction. diffusion does not require any membrane but osmosis require a selectively permeable membrane.

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What happens when a crystal of potassium permanganate is dropped in a glass tumbler containing water ?what conclusion can you draw?

Posted by Rajani Naik 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Bhavy Malhotra 4 years, 4 months ago

When we put potassium per magnet we will observe that after sometime the whole glass t u m b l e r get coloured Conclusion the particles of matter are continuously moving due to which the colour of potassium per magnet spread pinhole glass tumbler

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Write 1 to 20 symbol , atomic structure, molecular mass, charges and formula

Posted by Priya Graak 4 years, 4 months ago

CBSE > Class 09 > Science

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What do you mean by diffusion?Explain giving an example.

Posted by Rajani Naik 4 years, 4 months ago

CBSE > Class 09 > Science

3 answers

Satyam Chaubey 4 years, 4 months ago

The intermixing of particles of different states of matter with each other is known as diffusion Examples ; salt inter mix with water .Thos process is known as diffusion

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Kanav Dumra 4 years, 4 months ago

Diffusion is the process in which molecules of high concentration move to the direction of lower concentration to make uniform solution. Example :- dye moves to water to make uniform solution.

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Yogita Ingle 4 years, 4 months ago

Diffusion is the process wherein the molecules merge as a result of their kinetic energy of random motion. It occurs in liquids and gases because their molecules move randomly. The molecules move from a region of higher concentration to a region of lower concentration, down the concentration gradient, until the concentration equalizes throughout the medium.

Examples of Diffusion

A teabag immersed in a cup of hot water will diffuse into the water and change its colour.
A spray of perfume or room freshener will get diffused into the air by which we can sense the odour.
Sugar gets dissolved evenly and sweetens the water without having to stir it.

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Ice floats on water.why?

Posted by Sudama Ram 4 years, 4 months ago

CBSE > Class 09 > Science

3 answers

Pushprajsinh Rathod 4 years, 4 months ago

Ice floats on water because it is less dense than water.

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Kanav Dumra 4 years, 4 months ago

Ice has an open structure. Ice have more intermolecular space between particles than water. Thus, Ice floats on the water ?

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Gaurav Seth 4 years, 4 months ago

The mass per unit volume of a substance is called density (density = mass/volume). As the volume of a substance increases, its density decreases.

Liquids have lower density than that of solids. Water is also a liquid so it should also have less density than that of solid that is ice.

Though ice is a solid, but it has a cage like structure hence there are large number of empty spaces between its particles. These spaces are larger as compared to the spaces present between the particles of water. Thus for a given mass of water, volume of ice is greater than that of water. Hence, the density of ice is less than that of water. A substance with lower density than water can float on water. Therefore, ice floats on water.

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A boy is sitting on a merry go round which is moving with a constant speed of m/s.This means that the boy is a)at rest b) moving with no acceleration c) in accelerated motion d)moving with uniform

Posted by Rajni Rana 4 years, 4 months ago

CBSE > Class 09 > Science

2 answers

Shreya .. 4 years, 4 months ago

There is centripetal acceleration towards centre of the merry go round...which changes its velocity every moment...so answer should be (c)

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Gaurav Seth 4 years, 4 months ago

(c) In merry-go-round, the speed is constant but velocity is not constant, because its direction goes on changing i.e., there is acceleration in the motion. So, we can say that the boy is in accelerated motion.

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Name one organelle that can make some of its own protein in a plant cell and also mention one function of such an organelle.

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Gaurav Seth 4 years, 4 months ago

Plastids and MITOCHONDRIA are the two organelles who are known as semi-autonomous organelles because they make some of their own proteins and has their own genetic material. They are present in plant cell as well.

•Function of Mitochondria= They are the powerhouse of a cell, which provides energy to cell in form of ATP ( Adenosine Tri Phosphate) , its the energy currency of cell.

•Plastids=They store important chemical substances. It is of three types- Chromoplasts, Leucoplasts, Chloroplasts. Chloroplasts help in photosynthesis. Leucoplasts store starch, oils, protein granules

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Draw a plant cell and name seven important organelles found in it.

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

2 answers

Kanav Dumra 4 years, 4 months ago

I can't draw the structure here but I can name some organelles of plant cell. They are :- 1. Mitochondria , 2. Golgi apparatus , 3. Chloroplasts (plastid) , 4. Lysosomes , 5. Ribosomes , 6. Endoplasmic reticulum (SER, RER) , 7. Vacule.

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Shreya .. 4 years, 4 months ago

How to draw here??

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Describe an activity to demonstrate endosmosis and exosmosis. Draw a diagram in support of the activity.

Posted by Anjali Kumari 3 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 3 years, 4 months ago

Endosmosis

When a cell is kept in a hypertonic solution, the water starts moving into the cell from a region of higher concerntration to the region of lower concerntration is called endosmosis. As a result the cell swells up.

Activity -

Buy some raisens
Put them into a hypertonic solution (eg. water)
Now wait for some time and observe the raisens.
The raisens starts swelling up.
Observation - Through this activity we observe that after putting raisens in hypotonic solution the raisens swells up. Their is also an increase in thier weight.

Exosmosis

When a cell is kept in a hypotonic solution, the inner content of cell shrinks as the water moves from the region of higher concerntraion to the region of lower concerntration. This is called exosmosis.

Activity -

Buy some raisens
Put them in a hypotonic solution (eg. A sports drink with a lot of salts in it)
Wait for a while and observe that the cell starts shrinking
Observation - Through this actvity we observe that after putting raisens in a hypotonic solution the raisens starts losing water content and gets shrinked.

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draw the position time graph for non zero relative velocity

Posted by Narender Arora 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Meghna Thapar 4 years, 4 months ago

Zero relative velocity means the two objects are either stationary (both), or they are separated by the same displacement all the time. That also means that they both have the same speed, velocity and acceleration. They move in the same direction. So the acceleration - time graph will be exactly same for both.

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What is the function of cartilage and bone

Posted by Yug Kumar 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 4 years, 4 months ago

The main function of bones are:

Serve as storage of minerals.
Provide structural support.
Protect the internal organs of the body.

Cartilage: It serves as a shock absorber and allows the smooth movement of the bones at joints. They are mainly found in the nose, respiratory tract, and joints Fibrocartilage is found in the knee, and it is tough and inflexible. Elastic cartilage is found in-ear, epiglottis, and larynx. It is the most flexible cartilage.

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Which organelle would you associate with elimination of old and worn out cells? Why?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 4 years, 4 months ago

Lysosomes are the organelles which eliminate the old worn out cells.They are small bag-like structures spread in the cytoplasm.They have digestive enzymes filled inside by which they diges the old or worn out organelles of the cell.Lysosomes are also known as suiside bags. Because, during the disturbance in the cellular metabolism the lysosomes may burst and the digestive enzymes digest their on cell

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Will taking extra vitamins supplements help against COVID-19 infection?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Chirag Dahiya 4 years, 4 months ago

Yes

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How long does the virus survive on surfaces?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Smriti Garg 4 years, 4 months ago

48 hrs

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Can you get infected by COVID-19 through the air?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

5 answers

Kanav Dumra 4 years, 4 months ago

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Mishty Panchal 4 years, 4 months ago

If a man has covid 19 and he is sneaking without applying a mask, then his droplets will spread in the air. So the answer is yes.

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Satyam Chaubey 4 years, 4 months ago

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Faiza Tanvir 4 years, 4 months ago

Yes

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Ranjan Satpathy 4 years, 4 months ago

Yes we can get infected by COVID-19 through the air

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How can we always remember physics concept?

Posted by Ekta Ekta 4 years, 4 months ago

CBSE > Class 09 > Science

0 answers

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What precautions are you taking while buying groceries and when receiving a delivery at home these days?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

2 answers

Mishty Panchal 4 years, 4 months ago

We should sanitise them

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Smriti Garg 4 years, 4 months ago

Sanitise them before use

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What precautions are you taking these days before consuming fruits and vegetables?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Yashi ?? 4 years, 4 months ago

Precautions are as follows-- 1.) We wash the fruits with warm water and soda. 2.) Then we put them in a basket and put them outside so that because of the sun light they absorb the water.

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How can protect yourself from the infection of COVID-19?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Shivam Shekhar 4 years, 4 months ago

Yes we can able yo protect ourselves from the infection of COVID 19 by taking some small precautions like 1-We should always wear masks when we are going out 2-Never wear the same mask again and again 3-Always maintain the social distance 4-If we feel like cough , breathing problems , fever etc. Go hospital and give the blood samples for the test of Corona virus or anything else 5-If we come from red zone we will Quarantine ourself at least for 7 days By following these steps we can able to protect our self from the infection of covid 19

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What is the difference between self isolation, self quarantine and social distancing?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

2 answers

Shivam Shekhar 4 years, 4 months ago

Self Quarantine are to refrain from any contact with other individual for a period of time such as two weeks during the outbreak of contagious disease usually by remaining it once home Om and limiting contact with family members to reduce transmission of a contagious disease during outbreak individuals are typically ask by health officials to self for an following known contact with an infectious person or after returning from a region where case of the disease are widely reported as the coronavirus spreads across the country thousands of people who may have been exposed to the virus through travel abroad or contact with an infected person has been asked to self foreign time for two weeks to help contain the outbreak

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Shivam Shekhar 4 years, 4 months ago

in healthcare facilities isolation represent one of several measures that can be taken to implement infection control the prevention of contagious disease from being spread from a patient to other patient health care workers and visitors aur from outsider to a particular patient

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Why vaccine for COVID-19 is difficult to prepare and taking so long?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

3 answers

Kanav Dumra 4 years, 4 months ago

Development of the vaccine takes a lot of time and when there is virus, it takes more time than to make vaccine of other microbes

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Raj Vishwakarma 4 years, 4 months ago

Because covi 19 cause due to the virus and we have no antibiotic of viruse even we not hai antibiotic of dengue flu common cold because they arw viruses

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Mishty Panchal 4 years, 4 months ago

Development of a vaccine is a long process that can falter at any step. There is also the issue of effectiveness — how the vaccine performs in real-life conditions against efficacy, which is performance in ideal conditions during trials.Once a candidate is identified, its safety and efficacy have to be tested over three phases, as per protocols. A fourth stage involves collection and analysis of post-marketing data.For Covid-19, there are over 100 vaccines being developed across the world now, some from scratch, some from existing molecules developed for other diseases.

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Are antibiotics effective in preventing or treating COVID-19? Give reason for your answer.

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Mishty Panchal 4 years, 4 months ago

No, antibiotics do not work against viruses, only bacteria. The new coronavirus (COVID19) is a virus and, therefore, antibiotics should not be used as a means of prevention or treatment.

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What is mitochondria ,cytoplasm?

Posted by Krish Mishra 4 years, 4 months ago

CBSE > Class 09 > Science

2 answers

Kanav Dumra 4 years, 4 months ago

Mitochondria is an organelle of the cell which is used in the production of ATP type of energy. And cytoplasm is a fluid like substance in which all organelles of cells float.

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Shivam Shekhar 4 years, 4 months ago

An organelle found in large number in most cells in which the biochemical process of respiration and energy production occurs it has a double membrane the inner part being folded in words to form layers

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What are the symptoms of COVID-19?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Shivam Shekhar 4 years, 4 months ago

Covid-19 affects different people in different ways most infected peoples will develop mild to moderate illness and recover without hospitalization most common symptoms are fever dry cough and tiredness less common symptoms are aches and pains , sore throat, diarrhoea , conjunctivitis, headache, loss of taste or smell, Harsh on skin or discoloration of fingers or toes serious symptoms are difficulty in breathing or shortness of breath second chest pain or pressure 3 loss of speech or movement seek immediate medical attention if you have serious symptoms always call before visiting your doctor for health facilities people with mild symptoms who are otherwise healthy should manage their symptoms at home on average it takes 5 to 6days from when someone is infected with the virus for symptoms to show however it can take up to 14 days

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What does COVID-19 stands for?

Posted by Anjali Kumari 4 years, 4 months ago

CBSE > Class 09 > Science

1 answers

Shivam Shekhar 4 years, 4 months ago

CO means corona , VI means virus , D disease. Formally this disease was referred tu as 2019 novel coronavirus or 2019- nCoV the covid-19 virus is a new virus linked to the same family of viruses as severe acute respiratory syndrome s a r s and some type of common cold

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Convert m/ *** to km / hr (4) 110 m/ sec

Posted by Shagufta Zehra 4 years, 4 months ago

CBSE > Class 09 > Science