In sodium sulphate (Na₂SO₄), the mass percent of sodium, sulfur and oxygen is:

1. 32.4%, 45.05%, 22.6%

2. 22.6%, 45.05%, 32.4%

3. 32.4%, 22.6%, 45.05%

4. 45.05%, 32.4%, 22.6%

In a reaction A + B₂ →AB_2, 
A will act as a limiting reagent if :

Choose the correct option:

If 10 volumes of H₂ gas react with 5 volumes of O₂ gas, the volumes of water vapor produced would be:

1. 9

2. 8

3. 10

4. 11

The molar mass of naturally occurring Argon isotopes is 

Amount of HCl that would react with 5.0 g of manganese dioxide, as per the
given reaction will be:
4HCl_(aq) + MnO_2(s) ➡ 2H₂O_(l) + MnCl_2(aq) + Cl₂₍₂₎

1. 4.8 g

2. 6.4 g

3. 2.8 g

4. 8.4 g

The numbers 234,000 and 6.0012 can be represented in scientific notation as -

1. $2.34\times {10}^{-9} \mathrm{and} 6\times {10}^3$

2. 0.234 $\times {10}^{-6}$ and $60012\times {10}^{-9}$

3. $2.34\times {10}^{-9} \mathrm{and}$ $6.0012\times {10}^{-9}$

4. 2.34$\times {10}^5$ and 6.0012$\times {10}^0$

The number of significant figures in the numbers 5005, 500.0, and 126,000 are, respectively: