Match the following:

The number of  moles  present in 2.5 litres of 0.2 M  ${\mathrm{H}}_2{\mathrm{SO}}_4$ are:

1. 0.25

2. 0.5

3. 0.75

4. 0.2

Mark the species among the following that contains the highest number of atoms.

1. 4 g He

2. 46 g Na

3. 0.40 g Ca

4. 12 g He

The formula of an acid is ${\mathrm{HXO}}_2.$ The mass of 0.0242 moles of the acid is 1.657 g.
The atomic weight of X is:

 The maximum number of molecules is present in which of the following? 

1. 15 L of $H_2$ gas at STP

2. 5 L of $N_2$ gas at STP

3. 0.5 g of $H_2$ gas

4. 10 g of $O_2$ gas

An organic substance containing C, H, and O gave the following percentage composition :

C = 40.687%, H = 5.085% and O = 54.228%. The vapour density of this organic substance is 59.

The molecular formula of the compound will be:

1. C₄H₆O₄

2. C₄H₆O₂

3. C₄H₄O₂

4. None of the above

The number of valence electrons present in 0.53 grams of Na₂CO₃ is:

1. $3.01\times {10}^{23}$

2. $7.22\times {10}^{22}$

3. $12.046\times {10}^{23}$

4. $6.023\times {10}^{23}$

An element X has the following isotopic composition,

²⁰⁰X : 90%, ¹⁹⁹X : 8.0%, ²⁰²X : 2.0%

The weighted average atomic mass of the naturally occurring element X is closest to: 

100 mL of ${\mathrm{H}}_2{\mathrm{SO}}_4$ solution having molarity of 1M and density 1.5 g/mL is mixed with 400 mL of water. The molarity of the ${\mathrm{H}}_2{\mathrm{SO}}_4$ solution will be: (final density is 1.25 g/mL )