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How do we calculate valency???

Posted by Nanthithaa Varshini 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Ananya K 4 years, 11 months ago

If the number of electrons in the outer shell is between 1 to 4 the compound is said to have positive valency. For compound with electrons 4,5,6, or 7 the valency is determined by subtracting the electrons from eight

Rashi Aastha 4 years, 11 months ago

U can use electronic configuration Like in oxygen 2,6 which add up to 8 which is its atomic no. The general e.c. should be following 2,8,8 like that So it's missing two electrons So it will be -2

ANSWER

Wnat is osmosis

Posted by Gokul Settu 4 years, 11 months ago

CBSE > Class 09 > Science

4 answers

Priya Priya 4 years, 11 months ago

Diffusion of solvent molecules through semi-premerable from the region low concentration to region of high concentration form osmosis

Bhumikarani Pradhan 4 years, 11 months ago

The movement of water molecules through a selective permeable membrane along the conversation gradient is called osmosis. Osmosis is also defined as the water molecules from a region of its higher concentration through a semipermeable membrane.

Vedant Motewar 4 years, 11 months ago

Osmosis is the special type of diffusion in which it only take place in liquids.The concentration of solvent from region of higher concentration to the region of lower concentration. Like exchqnge of water in plants

Rashi Aastha 4 years, 11 months ago

a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.

ANSWER

What is elemant

Posted by Gokul Settu 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Rashi Aastha 4 years, 11 months ago

each of more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter. Each element is distinguished by its atomic number, i.e. the number of protons in the nuclei of its atoms.

ANSWER

What is the valency of iron

Posted by Pranav G Nath 4 years, 11 months ago

CBSE > Class 09 > Science

5 answers

Vaibhav Attri 4 years, 11 months ago

Valency of iron is 2,3

Anushka Agarwal 4 years, 11 months ago

Iron has 2 valencies: Ferrous has a valency of 2. Ferric has a valency of 3.

Bhumika Rani Pradhan 4 years, 11 months ago

The valency of iron is 2...

Lavishka Choudhary 4 years, 11 months ago

Valency of Iron (Fe) 2, 3 , atomic no. is 26

Shivam Kumar 4 years, 11 months ago

Atomic number is 26 Valency is 2,3

ANSWER

What ia sustainable development

Posted by Saumya Kashyap 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Lavishka Choudhary 4 years, 11 months ago

Sustainability is development that satisfies the needs of the present without compromising the capacity of future generations, guaranteeing the balance between economic growth, care for the environment and social well-being.

ANSWER

Explaine the difference between 2N and N^2

Posted by Utkarsh Dhiman 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Bhumika Rani Pradhan 4 years, 11 months ago

2N means to molecules of Nitrogen atom. N^2 two atoms of nitrogen in its one molecules. N^2 shows that two atoms are bonded with covalent bond, and it become nitrogen gas whereas 2N doesn't show any bond, it just show two numbers of nitrogen only.

ANSWER

What do you mean by nucleus

Posted by Nikhil Rajput 4 years, 11 months ago

CBSE > Class 09 > Science

3 answers

Beyon P Binoy 4 years, 11 months ago

Nucleus is the brain of the cell.

Bhumika Rani Pradhan 4 years, 11 months ago

Nucleus:- It is popularly called as the brain of cell. It is composed of double layer covering called head nuclear membrane. It has numerous pores called nuclear pores. They transfer the materials from inside the nucleus to cytoplasm. The nucleus contains chromosomes. When they are visible as rod-shaped structure only when the cell is about to divide. It encloses a liquid ground substance called nucleoplasm. It contains nucleolus and chromatin materials. Thank you...

Divya Gupta 4 years, 11 months ago

The cell nucleus is a membrane bound structure that contains a cell's hereditary information and controls it's growth and reproduction.It is the command center of a eukaryotic cell and usually the most notable cell organelle in both size and function

ANSWER

Why do you fall in the forward direction when a moving bus brakes to a stop and fall backwards when it accelerates from rest ?

Posted by Muskan Singh 4 years, 11 months ago

CBSE > Class 09 > Science

3 answers

Bhumika Rani Pradhan 4 years, 11 months ago

We fall backward when a bus accelerates from rest. This happens because the person and the bus both are in rest while the person is not moving as bus starts moving. The leg of the person starts along with the bus, but rest position of the body has tendency to remain in rest. Because of this, person falls backward if he or she is not alert.

Kamya Gandhi 4 years, 11 months ago

We fall in the forward direction when a moving bus brakes to a stop cuz of interia of motion and fall backwards when it accelerates from rest cuz of interia of rest

Beyon P Binoy 4 years, 11 months ago

Due to the Inertia of Rest and Inertia of Motion.

ANSWER

Moon and earth both exert force on each other then why moon don't fall on the surface of earth??

Posted by Zoya . 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Nikhil Kumar 4 years, 11 months ago

Because sun and other planets also exert force in moon that's why don't fall on earth

ANSWER

The frequency of a visible light of wavelength 600 nm is (speed of light = 3×10⁸ m/s), (1nm = 1‐⁹ m)

Posted by Jashith Sharma 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Jashith Sharma 4 years, 11 months ago

Options :- a) 50Hz b) 5 × 1014 Hz c) 0.5 × 1016 Hz d) 500 Hz Please I need the answer

Ananya K 4 years, 11 months ago

The wavelength of the light is, lamda = 600 nm =600 × 10-⁹ m

ANSWER

Why we are advised to take nutritional food when we are sick

Posted by Kavin Kathiresan A.P.A 4 years, 11 months ago

CBSE > Class 09 > Science

4 answers

Kamya Gandhi 4 years, 11 months ago

All the normal functions of the body get disturbed in case illness. So, a nourishing food is required, which is easily digestible and contains all the nutrients. This is the main reason that bland and nourishing food is advised to take during sickness.Because it helps in our nutritional growth

Yogita Ingle 4 years, 11 months ago

All the normal functions of the body get disturbed in case illness. So, a nourishing food is required, which is easily digestible and contains all the nutrients. This is the main reason that bland and nourishing food is advised to take during sickness.

Khushi Chauhan 4 years, 11 months ago

Hdis

Roshan Pandey 4 years, 11 months ago

Because it helps in our nutritional growth

ANSWER

Anand leaves his house at 8.30 A.M for his school. The school is 2 km away and classes start at 9.00 A.M. If he walks at a speed of 3 km/h for the first kilometre, at what speed should he walk the second kilometre to reach just in time?

Posted by Mishika Pandey 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Ananya K 4 years, 11 months ago

A--------------B--------------C Let A is Anand house B is 1km distance apart from his house C is school We know time = distance --------------- Speed tAB = 1 --- 3 tAB is the time taken from A to B tBC = 1 - 1 =1 ---. ---. --- hours 2. 3. 6 So, speed = distance. 1 --------------- = -------- time. (1/6) = 6 km/h

ANSWER

Why common salt is said to be a substance and salty water a mixture?

Posted by Vansh Arora 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

Common salt is a pure substance(compound) because it is made up of 2 types of elements, i.e., Sodium and Chlorine. These 2 substances cant be separated by physical processes. While, salty water is a mixture of water and salt and can be separated by physical processes like evaporation.

ANSWER

Give an example of atoms,molecules and Ion

Posted by Asika A 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Bhumika Rani Pradhan 4 years, 11 months ago

1.ATOMS :- Hydrogen, Carbon, Oxygen, Phosphorus, Sulphur, Iron, Copper, Lead, Silver, etc. 2.MOLECULES :- Water, Ammonia, Carbon dioxide, Hydrogen Sulphide, Sulphuric Acid, Glucose, Backing Powder, Common Salt, Limestone or Calcium Carbonate, etc. 3. IONS :- Na+, K+, Ca2+, etc.

ANSWER

A solution contains 40g of common salt in 320g of water. Calculate the concentration in terms of the mass by mass percentage of the solution

Posted by Akshaya Shree 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Harsh Saini 4 years, 11 months ago

Mass of solute=40g ". ". Solvent= 320g Mass of solution= mass of solute+ mass of solvent 40+320 = 360 Mass by mass formula= Mass of solute × 100 = Mass of solvent 40 x 100 = 4 × 100 now do it by your self 360. 36

Yogita Ingle 4 years, 11 months ago

Mass of solute = 40g

Mass of solvent = 320g

Mass of solution = Mass of solute + Mass of solvent
= 40g + 320g
= 360gMass percentage of solution = (Mass of solute/Mass of solution)x100
=   40 / 360 x 100

= 11.1%

ANSWER

Describe plasma membrane and its functions ?

Posted by K.Kaviya Ix A 9032 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Vidhi Srivastav 4 years, 11 months ago

It is a jelly like structure surrounded by the cell wall making selective things passing through it ♦ It's Function are :- # It provides rigidity to cell # It do not allow every thing passing through it # It helps in changing of substance in the cell only ♦ Mark me as the brainliest answer

ANSWER

Explain functions of the cells ?

Posted by K.Kaviya Ix A 9032 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Vidhi Srivastav 4 years, 11 months ago

The basic processes of life include organization, metabolism, responsiveness, movements, and reproduction. In humans, who represent the most complex form of life, there are additional requirements such as growth, differentiation, respiration, digestion, and excretion.

ANSWER

State the law of conservation of mass. Is this law applicable to the chemical reaction? Elaborate your answer with the help of an example?

Posted by Sneha Singh 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 4 years, 11 months ago

The law of conservation of mass states that mass in an isolated system is neither created nor destroyed by chemical reactions or physical transformations.

According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

The law of conservation of mass is useful for a number of calculations and can be used to solve for unknown masses, such the amount of gas consumed or produced during a reaction.

It is applicable in a chemical when the the mass of the products in a chemical reaction is equal to the mass of the reactants.

But it is not applicable in a nuclear fusion as some of the mass is generated as energy.

Sneha Singh 4 years, 11 months ago

Ch 3 Atoms & Molecules

ANSWER

Distinguish between: a) Physical change and Chemical change any 3 point

Posted by Vedant Bhadra 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 4 years, 11 months ago

Physical Change	Chemical Change
When a substance undergoes a physical change, its composition remains the same despite its molecules being rearranged.	When a substance undergoes a chemical change, its molecular composition is changed entirely. Thus, chemical changes involve the formation of new substances.
Physical change is a temporary change.	A chemical change is a permanent change.
A Physical change affects only physical properties i.e. shape, size, etc.	Chemical change both physical and chemical properties of the substance including its composition
A physical change involves very little to no absorption of energy.	During a chemical reaction, absorption and evolution of energy take place.
Some examples of physical change are freezing of water, melting of wax, boiling of water, etc.	A few examples of chemical change are digestion of food, burning of coal, rusting, etc.
Generally, physical changes do not involve the production of energy.	Chemical changes usually involve the production of energy (which can be in the form of heat, light, sound, etc.)

Vedant Bhadra 4 years, 11 months ago

Pls tell me

ANSWER

What is paramchyma tissue

Posted by Daksh Choudhary 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

Consist of live unspecialized cells having thin cell wall.
They are loosely packed and have large intercellular space (space between the cells).
Provides support to the plant and present in all parts like roots, stems, leaves, fruits and seeds.
Storage of food (eg. Fruits) and water (in stems eg. cactus) is the main function.
Sometimes, these tissues also contain chlorophyll and perform photosynthesis, and known as chlorenchyma.
In case of aquatic plants, parenchyma is modified into aerenchyma.
Aerenchyma is the tissues having large air cavities which provides buoyancy to the plants and help them to float.

ANSWER

Iron pins from sands is which sepration

Posted by Shubham Sharma 4 years, 11 months ago

CBSE > Class 09 > Science

5 answers

Gunu Ahmed 4 years, 11 months ago

Separation through magnet

Beyon P Binoy 4 years, 11 months ago

Seperation through magnet

Aastha Tiwari ? 4 years, 11 months ago

Using magnet.. Magnet will attract all the iron pins and thus it will be separated

Priyanshu Raj 4 years, 11 months ago

Using magnets

Riya Mangang 4 years, 11 months ago

By using magnets

ANSWER

Chemical name of sulphuric acid

Posted by Riya Mangang 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Beyon P Binoy 4 years, 11 months ago

H2SO4 - sulphuric acid

Divya Gupta 4 years, 11 months ago

Chemical name for sulphuric acid is H2SO4

ANSWER

Chemical formula of lead(ii) chloride

Posted by Riya Mangang 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

N K 4 years, 11 months ago

Chemical formula of chloride is Cl

Om Shivhare 4 years, 11 months ago

Mam we have to write thory in 2.3 exercise

ANSWER

Name the most abundant element in the earth's crust

Posted by Tarun Sharma 4 years, 11 months ago

CBSE > Class 09 > Science

5 answers

Aastha Tiwari ? 4 years, 11 months ago

Oxygen

Rohit Gupta 4 years, 11 months ago

Oxygen

Yogita Ingle 4 years, 11 months ago

The most abundant element in the earth’s crust is oxygen (46. 1%). The chemical formula of oxygen also known as dioxygen is O₂. This formula is given so because oxygen usually combines with another oxygen by forming a covalent bond.

Kamya Gandhi 4 years, 11 months ago

Sorry for blah right ans. Is The mass-abundance of the nine most abundant elements in the Earth's crust is approximately: oxygen 46%, silicon 28%, aluminum 8.3%, iron 5.6%, calcium 4.2%, sodium 2.5%, magnesium 2.4%, potassium 2.0%, and titanium 0.61%.

Kamya Gandhi 4 years, 11 months ago

Blah

ANSWER

Chemical formula of lead(ii)

Posted by Riya Mangang 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Rohit Gupta 4 years, 11 months ago

Pb

Kamya Gandhi 4 years, 11 months ago

Pb

ANSWER

How are simple tissues different from complex tissue in plants

Posted by Nadeem Ansari 4 years, 11 months ago

CBSE > Class 09 > Science

1 answers

Yogita Ingle 4 years, 11 months ago

Simple tissue	Complex tissue
Simple tissues consist of only one type of cells	These tissues are made up of more than one type of cells.
The cells of simple tissue perform similar function.	The cells of complex tissue may perform different functions.
Example of simple tissues are collenchymas, parenchyma.	Examples of complex tissues are xylem and phloem.

ANSWER

What is homoginius mixture

Posted by V.Sriman Venkatesan 9E Sriman 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Yogita Ingle 4 years, 11 months ago

Mixtures which have uniform composition throughout are called Homogeneous Mixture. For example – mixture of salt and water, mixture of sugar and water, air, lemonade, soda water, etc.

Mixture of salt in water is an example of homogeneous mixture. In this mixture, the boundary of salt and water cannot be differentiated. When a ray of light is passed through the mixture of salt and water, the path of light is not seen.

Nadeem Ansari 4 years, 11 months ago

A homogenous mixture is a solid, liquid or gaseous mixture that had the same proportions of its components throughout any given sample.

ANSWER

Area under velocity-time graph gives:

Posted by Ashish Jj 4 years, 11 months ago

CBSE > Class 09 > Science

2 answers

Sarita Panda 4 years, 11 months ago

Magnitude of displacement or distance...

Nanthithaa Varshini 4 years, 11 months ago

Displacement

ANSWER

the velocity of a given particle is represented by the equation week was 2534 plus tuti cube minus 3 x square + 9 calculate acceleration of the object time is to second and calculate instantaneous acceleration

Posted by Muskan Maida 4 years, 11 months ago

CBSE > Class 09 > Science

0 answers

ANSWER

Types of stemmers

Posted by Mohan Karthik.S 4 years, 11 months ago

CBSE > Class 09 > Science

0 answers

ANSWER

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