Chemistry Test - 1

Number of moles of sulphur = 32/32 = 1 mole

One mole of Na₂S₂O₃ will be obtained from 2 moles of sulphur.

Mole of Na₂S₂O₃ obtained from 1 mole of sulphur = ½ = .50 mole

Number of moles of ammonia = 4.25/17 = 0.25 mol

Number of molecules in 0.25 mol of ammonia = 0.25 x 6.022 x 10²³

 = 1.5 x 10²³

46 g 28 g

It is clear from the above equation that number of moles of ethene formed = Number of moles of ethanol used

Number of moles of ethene formed = 5.6/28 = 0.2

M = n/V

V = n/M = 0.2/0.1 = 2 L

Mass of 1 atom of helium = 4 amu

So, in 100 amu, the number of helium atoms = 100/4 = 25 

Nitrogen is present in largest amount in the atmosphere. So it has the highest partial pressure in the atmosphere.

The partial pressure of A in a mixture of A and other gases is the total pressure multiplied by the mole fraction of A.

In the present case,

Mole fraction of hydrogen =1/(1+(1/2)) = 2/3

The partial pressure of Hydrogen = 2/3 of total pressure

PV = ZnRT

Here, n (number of moles)=mass(W) / molar mass(M)

Then, PM=( W/V )ZRT

PM = ZdRT (where, M is molecular mass and d is density) [W/V=d (density)]

Substituting the values,

(1)(30) = Z(0.4)(0.082)(773) 

Z = 1.183 > 1

Thus, forces are repulsive.