Match the following:

4.4 g of an unknown gas occupies 2.24 litres of volume at NTP. The gas may be: 

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 weight of 1x10²³ molecules of CuSO₄.5H₂O is: 

1. 34.42 g

2. 41.42 g

3. 54.44 g

4. 68.94 g

The mass of carbon present in 0.5 mole of K₄[Fe(CN)₆] is:

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 amount of copper (in grams) that can be obtained from 100 g of
copper sulphate (CuSO₄) is:

The haemoglobin from the red blood corpuscles contains approximately 0.33%  iron
by mass. The molar mass of haemoglobin is 67,200. The number of iron atoms in each molecule of haemoglobin is :
(atomic mass of iron=56):