In an iron oxide, the mass percent of iron and oxygen are 69.9 and 30.1, respectively. The empirical formula of the oxide of iron will be:

1. Fe₃O₂

2. Fe₂O₂

3. Fe₂O₃

4. Fe₃O₄

The average atomic mass of chlorine using the following data would be -

1. 38.4527 u

2. 37.4527 u

3. 36.4527 u

4. 35.4527 u

The molar mass of naturally occurring Argon isotopes is 

Burning a small sample of welding gas (constituted of C and H only)  in oxygen gives 3.38 g carbon dioxide, 0.690 g of water, and no other products. A volume of 10.0 L (measured at STP) of this welding gas is found to weigh 11.6 g. Molecular formula of welding gas would be -

1. C₂H₂

2. C₂H₆

3. CH

4. C₂H₄