English Medium इयत्ता ९ - CBSE Question Bank Solutions

Write the cations and anions present, if any, in the following : 

1. CH₃COONa 
2. NaCl
3. H₂
4. NH₄NO3

Fill in the following blanks :

1 mole contains .............. atoms, molecules or ions of a substance.

If one mole of nitrogen molecules weighs 28 g, calculate the mass of one molecule of nitrogen in grams.

Calculate the number of molecules present in a drop of chloroform (CHCl3) weighing 0.0239 g.

(Atomic masses : C = 12 u ; H = 1 u ; Cl = 35.5 u)

If 1 gram of sulphur dioxide contains x molecules, how many molecules will be present in 1 gram of oxygen ?

(S = 32 u ; O = 16 u)

Which contains more molecules, 10 g of sulphur dioxide (SO2) or 10 g of oxygen (O2) ?

(Atomic masses : S = 32 u ; O = 16 u)

How many atoms are present in a PO₄ ^3– ion?

How many atoms are present in a `PO_4^(3-)` ion?

Look at Fig. 1.3 and suggest in which of the vessels A,B, C or D the rate of evaporation will be the highest? Explain.

Comment on the following statements:

Evaporation produces cooling.

Comment on the following statements:

Rate of evaporation of an aqueous solution decreases with increase in humidity.

What is the fraction of the mass of water due to neutrons?

Express each of the following in kilograms

5.84 × 10⁻³ mg

Express each of the following in kilograms

58.34 g

Express each of the following in kilograms

0.584 g

Express each of the following in kilograms

58.34 g

Express each of the following in kilograms

5.873×10⁻²¹g

Compute the number of ions present in 5.85 g of sodium chloride

A group of atoms carrying a fixed charge on them is called ————.

Which of the following statements about Rutherford’s model of atom are correct?

(i) considered the nucleus as positively charged

(ii) established that the α–particles are four times as heavy as a hydrogen atom

(iii) can be compared to solar system

(iv) was in agreement with Thomson’s model