English Medium इयत्ता ९ - CBSE Question Bank Solutions for Science

Copper sulphate reacts with sodium hydroxide to form a blue precipitate of copper hydroxide and sodium
sulphate. In an experiment, 15.95 g of copper sulphate reacted with 8.0 g of sodium hydroxide to form
9.75 g of copper hydroxide and 14.2 g of sodium sulphate. Which law of chemical combination is illustrated by this data ? Give reason for your choice.

Potassium chlorate decomposes, on heating, to form potassium chloride and oxygen. When 24.5 g of potassium chlorate is decomposed completely, then 14.9 g of potassium chloride is formed. Calculate the mass of oxygen formed. Which law of chemical combination have you used in solving this problem ?

For the symbols H, D and T, write the subatomic particles (protons, neutrons and electrons) found in each one of them.

Which of the following statement is correct about the atom of an element ?

An ionic compound will be formed by the combination of one of the following pairs of elements. This pair of elements is :

Find the mass of 2 moles of nitrogen atoms.

How many atoms are there in exactly 12 g of carbon-12 element ? (C = 12 u)

Calculate the number of moles in 12.044 × 1025 atoms of phosphorus.

Which has more atoms, 50 g of aluminium or 50 g of iron ? Illustrate your answer with the help of calculations.

(Atomic masses : Al = 27 u ; Fe = 25 u)

A few drops of ‘Dettol’ when added to water the mixture turns turbid. Why?

What is the physical state of water at 0°C. 

What is the physical state of water at 250°C.

What is the physical state of water at 100ºC?

The chemical symbol for nitrogen gas is ______.

Which of the following has maximum number of atoms?

A change in the physical state can be brought about

Does the solubility of a substance change with temperature? Explain with the help of an example.

You are provided with a fine white coloured powder which is either sugar or salt. How would you identify it without tasting?

A sample of vitamic C is known to contain 2.58 ×10²⁴ oxygen atoms. How many moles of oxygen atoms are present in the sample?

Dalton’s atomic theory successfully explained

(i) Law of conservation of mass

(ii) Law of constant composition

(iii) Law of radioactivity

(iv) Law of multiple proportions