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ANSWER

Why did Mendeleev leave some gaps in his periodic table?

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

2 answers

Deepak Silaych 6 years ago

Mendeleev proposed that there are many element that was not discovered at that time but can be discovered in future therefore he leave blanks or gaps in his periodic table naming the "eka (element before the gap)".

Saurabh Singh 6 years ago

For more elements which invent in future

ANSWER

What were the two criteria used by Mendeleev in creating his periodic table?

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

1 answers

Deepak Silaych 6 years ago

1. He arranged all element in increasing Atomic Mass 2. He created rows on the bases of nature of element oxide and hydrides

ANSWER

What is the difference between two reaction 1 mg+2hcl

Posted by Mohit Bharwani 6 years ago

CBSE > Class 10 > Science

1 answers

Deepak Silaych 6 years ago

2nd reaction

ANSWER

Both soaps and detergents are some types of salt. What is the difference between them ?Describe in brief the cleansing action of soap. why do soap not form lather in hard water?List two problems that arise due to the use of detergents instead of soaps ( 5 marks )

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

1 answers

Meghna Thapar 6 years ago

Difference between soaps and detergents:

Soaps

Detergents

(i)Soaps are biodegradable.

(ii) Soaps have relatively weak cleansing action.

(i) Detergents are not biodegradable.

(ii) Detergents have a strong cleansing action.

Cleaning action of soap:

Soaps are molecules in which the two ends have differing properties, one is hydrophilic, that is it dissolves in water, while the other end is hydrophobic, that is it dissolves in hydrocarbons. When soap is at the surface of water the hydrophobic ‘tail’ of soap will not be soluble in water and the soap will align along the surface of water with the ionic end in water and the hydrocarbon ‘tail’ protruding out of water. Inside water, these molecules have a unique orientation that keeps the hydrocarbon portion out of the water. This is achieved by forming clusters of molecules in which the hydrophobic tails are in the interior of the cluster and the ionic ends are on the surface of the cluster. This formation is called a micelle. Soap in the form of a micelle is able to clean, since the oily dirt will be collected in the centre of the micelle. The micelles are large enough to scatter light. Hence a soap solution appears cloudy.

When soap is used for washing clothes with hard water, a large amount of soap in water is reacting with the calcium and magnesium ions of hard water to form an insoluble precipitate called scum.

Disadvantage of using detergents:

Detergents are not biodegradable and hence cause water pollution.

ANSWER

What is the major problem in harnessing nuclear energy ?

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

1 answers

Deepak Silaych 6 years ago

1. Limited amount of uranium or nuclear fuel. 2. Management of nuclear power plant is difficult. 3. Leakage in nuclear power can cause hazardous problems

ANSWER

What is a clean fuel ?

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

1 answers

Abhilash Anandhan 6 years ago

Clean fuel means which will not pollute the earth.....like CNG gas... battery vehicles.... It is alternate way to minimise the usage of petroleum

ANSWER

Why does the use of dry wood as domestic fuel not considered to be good ?

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

1 answers

Abhilash Anandhan 6 years ago

Because it emits lot of carbon dioxide... which makes our earth global warming and pollutes the air

ANSWER

Define water o crystallization

Posted by Kai Hiwatari 6 years ago

CBSE > Class 10 > Science

2 answers

Deepak Silaych 6 years ago

Element Crystal like gypsum (CaSO4.2H20) contain water molecules which decompose on heating change the physical and chemical properties . These water molecules are called water of crystallization.

Deepak Silaych 6 years ago

Element Crystal like gypsum (CaSO4.2H20) contain water molecules which decompose on heating change the physical and chemical properties . These water molecules are called water of crystallization

ANSWER

What is amphoteric?

Posted by Satish Ranjan 6 years ago

CBSE > Class 10 > Science

4 answers

Kusha Lamba 6 years ago

Amphoteric Oxides are those oxides which show both acidic and basic behaviour. They react with both acid and base to form salt and water. E.g: Aluminium Oxide and Zinc Oxide.

Deepak Silaych 6 years ago

CORRECT ANSWER: Amphotric oxides are those oxides which show both acidic and basic nature that why they react with both acid and base. The metal in amphoric oxides are called amphoteric metals.

Kai Hiwatari 6 years ago

Ampoteric oxides are oxides that react with both acids and bases

Kunnaram Choudhary 6 years ago

Reacts with both acids and and bases . Ex aluminium,zinc etc.

ANSWER

Diff b/w ac generator and dc generator

Posted by Saurabh Singh 6 years ago

CBSE > Class 10 > Science

2 answers

Ac generator produces alternate current where as the Dc generator produces direct current.

Neha Kothari 6 years ago

In ac generator we use slip rings While In dc we use split rings

ANSWER

What is a sperical mirror ?

Posted by Manminder Singh Mani 6 years ago

CBSE > Class 10 > Science

3 answers

Saurabh Singh 6 years ago

Mirror whose reflected surface is curved

Shailaja Singh 6 years ago

Spherical mirror are round in shape ,it maybe concave or convex mirror

Manminder Singh Mani 6 years ago

Cancave mirror and canvex mirror

ANSWER

Mandilev periodic table limitations

Posted by Narottam Yadav 6 years ago

CBSE > Class 10 > Science

2 answers

Neha Kothari 6 years ago

1.isotopes are placed in a same grup instead of having dfffrt mass. 2.some havier elements placed before lighter 3.correct position to istope couldn't assigned in his periodic table

Kunnaram Choudhary 6 years ago

Some of the drawbacks of mendeeleve's periodic table are: 1.he considered atomic mass as main category to classify elements. 2.he broke his own law while arranging the anomolous pairs of tellurium and iodine.

ANSWER

Why is a solar cooker painted black from outside

Posted by Gudiya Kumar Patel 6 years ago

CBSE > Class 10 > Science

4 answers

The black colour is ideal for absorbing much heat and hence it is paninted with black colour

Saurabh Singh 6 years ago

Because black colour absorb extremely heat

Manminder Singh Mani 6 years ago

Solor cooker is painted black to absorb a more heat

Thanuja Lakshmi 6 years ago

Solar cooker is painted black to absorb more heat cause ultimately we want to cook food faster .. and so more heat is required.

ANSWER

Graphically and mathematically prove the ohm 's law.

Posted by Rani Mishra ??? 6 years ago

CBSE > Class 10 > Science

2 answers

Manminder Singh Mani 6 years ago

V=I/R is a formula explain is a graph

Broken Soul 6 years ago

V=IR explain kro aur graph bna do

ANSWER

What is the function of aqueous humor in the eye ball???

Posted by Class 12 6 years ago

CBSE > Class 10 > Science

2 answers

Manminder Singh Mani 6 years ago

Control the light ray enter the eye help in a formation image on retina

Harshita Baweja 6 years ago

1 control the light Ray's entering in our eye 2help in the formation of image on retina

ANSWER

What is Lateral Deviation?

Posted by Arshdeep Kaur 6 years ago

CBSE > Class 10 > Science

1 answers

Harshita Baweja 6 years ago

It is the prependicular distance between emergent Ray and incident ray

ANSWER

What is tha function of nephrons

Posted by Kashif Khan 6 years ago

CBSE > Class 10 > Science

3 answers

Harshita Baweja 6 years ago

1 purification of human blood 2 maintain the osmotic pressure through out the body 3make the body diseases free

Ankit Gupta 6 years ago

Hi diksha

Karan Katariya 6 years ago

Bilkul sahi

ANSWER

Chemical reactions and equations Ques. How to find whether the element is solid,liquid,gas,aqueous when writing a chemical equation

Posted by Akshat Joshi 6 years ago

CBSE > Class 10 > Science

1 answers

Rahul Lakhani 6 years ago

By the symobol that noted For example when we right Na(s), here this 's' shows that Na is solid.

ANSWER

AB and CD, two spherical mirrors, form parts of a hollow spherical ball with its centre at O as shown in the diagram. If arc AB = :1/2 arc CD, what is the ratio of their focal lengths ?

Posted by Nancy Kansal 6 years ago

CBSE > Class 10 > Science

0 answers

ANSWER

What are 4 factors that can lead to speciation

Posted by Prabal Das 6 years ago

CBSE > Class 10 > Science

2 answers

Kush Nagar 6 years ago

Say thanks to me I have answered you

Kush Nagar 6 years ago

•Geographical isolation. •Genetic drift. •Natural selection. •Reduction in Gene flow. •Reproductive isolation.

ANSWER

Name the excretry ore of mercury

Posted by Sumit Kumar Sumit Kumar 6 years ago

CBSE > Class 10 > Science

5 answers

Cinnabar

Saurabh Singh 6 years ago

HgS

Mayank Goyal 6 years ago

Cinnabar

Harshita Baweja 6 years ago

Cinnabar HgS

Varsha Katambe 6 years ago

Cinabar

ANSWER

State the conditions for autotrophic nutrition and name the by-product. Mention the source of this by-product

Posted by Misbah Arsheen 6 years ago

CBSE > Class 10 > Science

1 answers

Aadya Singh 6 years ago

Conditions necessary for Autotrophic nutrition are chlorophyll, sunlight, water and carbon dioxide... And the by product is oxygen..

3Thank You

ANSWER

What are the method used by the plants to get rid of excretory products ? for 3 marks

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

1 answers

Harshita Baweja 6 years ago

1.food 2dry leaves 3oxygen The things which we use in our daily life are actually waste product of plant

ANSWER

salt A commonly used in bakery products , on heating gets converted into another salt B; which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky .Identify A , B and C( for 3 marks )

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

3 answers

Sumit Kumar Sumit Kumar 6 years ago

A-baking soda ,B-washing soda ,C-carbon dioxide

Aadya Singh 6 years ago

C - carbon dioxide ?

Niteshvashu Goswamig 6 years ago

C-chlorine,B-NaHCo3 sodium hydrogen carbonate A-Na2Co3 sodiumcarbonate

ANSWER

state the role of bacteria in the mouth. Suggest a method to prevent tooth decay

Posted by Nitin Tiwari 6 years ago

CBSE > Class 10 > Science

2 answers

Due to intake of sugary products bacterial growth is absorbed in our mouth and the pH of mouth will fall from 7to 5.5. *Gogle ur mouth soon after eating with plenty of water. *Use basic toothpaste to clean ur tooth twice a day so that it neutralizes the acid in ur mouth.

Neha Kothari 6 years ago

When the pH of our mouth falls below 5.5 than the bacteria present in our mouth breaks down the sugar present in our mouth nd make it acidic .which lead to tooth decay. *Prevention 1.regular brushing 2.gargle with mouth cleaner

ANSWER

Lateral inversion and lateral displacement

Posted by Vishal Kumar 6 years ago

CBSE > Class 10 > Science

1 answers

Niteshvashu Goswamig 6 years ago

When we stand in front of a mirror and put our right hand up then the image in the mirror we see is is put his left hand up is lateral inversion

ANSWER

What is the function of Heart?

Posted by Ramesh Kumar 6 years ago

CBSE > Class 10 > Science

3 answers

Class 12 6 years ago

It is the main pumping organ for an organism body which pumps the blood through out the body to meet oxygen requirements of different organs or tissues of the body❤

Niteshvashu Goswamig 6 years ago

Clean deoxygenated blood into oxygenated blood