Two moles of chlorine atoms are present in how many grams of chlorine gas?

Calculate:

How many gram atoms of sodium is present in $115 \mathrm{g}$ sodium?

The molecular mass of methane $\left({\mathrm{CH}}_4\right)$ is $16 \mathrm{u}$.

What is the mass of 1 GMM of CH4

Calculate:

Mass of 5 gram atoms of calcium.
[Hint: Gram atoms mass: $\mathrm{Ca}=40 \mathrm{g}$]

A and B react to produce C according to the following chemical equation 
$2\mathrm{A} + \mathrm{B} \to 2\mathrm{C}$

A, B and C are the formulas for three gaseous substances. The vapour densities of A and B are 32 and 16 respectively. Find out the vapour density of C. 

Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation:

$2\mathrm{NaOH} + {\mathrm{CuSO}}_4\to {\mathrm{Na}}_2{\mathrm{SO}}_4+ \mathrm{Cu}{\left(\mathrm{OH}\right)}_2\downarrow$

i) What mass of copper hydroxide is precipitated by using $200 \mathrm{gm}$ of sodium hydroxide?

$[\mathrm{H} = 1, \mathrm{O} = 16, \mathrm{Na} = 23, \mathrm{S} = 32, \mathrm{Cu} = 64]$

(ii) What is the colour of the precipitate formed?

Study the following table.

Which two compounds have least weight of oxygen? (molecular weights of compounds are given in brackets)