Q1 of 27 Page 47

How many grams of carbon and oxygen are required to get the same number of atoms as is present in one gram of helium?

Atomic mass of carbon = 12

Atomic mass of oxygen = 16


Atomic mass of helium = 4


Mass of helium = 1g


For carbon:



By putting the values, we get:



By applying criss cross method:



We get:


Mass of carbon × 4 = 12 × 1g



Mass of carbon = 3g


Thus, 3 grams of carbon is required.


For oxygen:



By putting the values, we get:



By applying criss cross method:



We get:


Mass of oxygen × 4 = 16 × 1g



Mass of oxygen = 4g


Thus, 4 grams of oxygen is required.


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7

Calculate the following.

Volume of 170 g ammonia at STP.


(GMM/GFM: H2O - 18 g, CaCO3 - 100 g, CO2 - 44 g, NH3 - 17 g)

 7

Calculate the following.

The mass of 112 L CO2 gas at STP and the number of molecules.


(GMM/GFM: H2O - 18 g, CaCO3 - 100 g, CO2 - 44 g, NH3 - 17 g)

 2

Examine the samples given:

a. 20 g of He


b. 44.8 L of NH3 at STP


c. 67.2 L of N2 at STP


d. 1 mol of H2SO4


e. 180 g of water


Arrange the samples in increasing order of the number of molecules in each.

 2

Examine the samples given:

a. 20 g of He


b. 44.8 L of NH3 at STP


c. 67.2 L of N2 at STP


d. 1 mol of H2SO4


e. 180 g of water What will be the ascending order of the total number of atoms in each sample?