Worksheet

1.

How many significant figures are present in the following? (iii) 5005

2.

Convert the following into basic units: (i) 28.7 pm

3.

Round up the following upto three significant figures: (iii) 0.04597

4.

Calculate the number of atoms in each of the following (iii) 52 g of He.

5.

Pressure is determined as force per unit area of the surface. The SI unit of pressure, pascal is as shown below:
$1Pa = 1N m^{-2}$
If mass of air at sea level is 1034 g $cm^{-2}$, calculate the pressure in pascal.

6.

Which one of the following will have the largest number of atoms?

a. 1 g Au (s) b. 1 g Na (s) c. 1 g Li (s) d. 1 g of $Cl_2(g)$

7.

A large piece of jewelry has a mass of 132.6 g. A graduated cylinder initially contains 48.6 mL water. When

the jewelry is submerged in the graduated cylinder, the total volume increases to 61.2 mL.

Determine the density of this piece of jewelry.

a.

10.52kg/ml

b.

1.052 g/ml

c.

10.52g/ml

d.

1.052kg/ml

8.

If the speed of light is $3.0 \times 10^8 m s^{-1}$, calculate the distance covered by light in 2.00 ns.

9.

A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it 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. Calculate (i) empirical formula

10.

In a reaction $A + B_2 \rightarrow AB_2$ Identify the limiting reagent, if any, in the following reaction mixtures. (i) 300 atoms of A + 200 molecules of B

11.

Convert the following into basic units: (iii) 25365 mg

12.

A welding fuel gas contains carbon and hydrogen only. Burning a small sample of it 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. Calculate (ii) molar mass of the gas

13.

Total number of electrons in nitride ion ?(No is Avogadros constant)

a.

7xNo

b.

10No

c.

12No

d.

9No

14.

Which law states that “mass can neither be created nor destroyed”?

a.

Law of definite proportions

b.

Law of conservation of mass

c.

Avogadro law

d.

Gay Lussac’s law

15.

the ______ is the length of the path travelled by light in vaccum during a time interval of 1/299792458 of a second

a.

kilogram

b.

second

c.

ampere

d.

metre

16.

How many significant figures should be present in the answer of the following calculations? (i) $\frac{0.02856 \times 298.15 \times 0.112}{0.5785}$

17.

In three moles of ethane ($C_2H_6$), calculate the following: (iii) Number of molecules of ethane.

18.

Calculate the density of aluminum if 27.6 cm3 has a mass of 74.6 g.

a.

2.7

b.

1.7

c.

3.7

d.

2.5

19.

Calcium carbonate reacts with aqueous HCl to give $CaCl_2$ and $CO_2$ according to the reaction, $CaCO_3 (s) + 2 HCl (aq) \rightarrow CaCl_2 (aq) + CO_2(g) + H_2O(l)$. What mass of $CaCO_3$ is required to react completely with 25 mL of 0.75 M HCl?

20.

In three moles of ethane ($C_2H_6$), calculate the following: (ii) Number of moles of hydrogen atoms.