Chemistry

 

1. A Compound Consists of 80% by mass of carbon and 20 by mass of hydrogen. Calculate its empirical formula.

Ans:   Empirical Formula C1:H3 CH3

C:H

80/12:20/1

moles = 6.667/6.667:20/6.667

divide by he smallest

 => 1:3

2.Which separating techniques can be used to 

separate a solution(mixture of a solute and solvent).

Ans: Simple Distillation

3 Study the electronic configuration of 

sodium and chorine atoms

-sodium: 2.8.1

-chorine: 2.8.7

what is the charges of sodium atom?

Ans :Positive Charge

4.which non metal is used to sterilize water?

Ans: Chlorine

5.Define the term isotopes?

Ans: I isotopes are atoms of the same element

     having the same number of of protons

     but different number of neutrons.

6. An Acid is said to have a sour taste.

What particle of an ACID is responsible 

for the sour taste?

Ans: Hydrogen ion:  Acidity is determined by 

the number of Hydrogen ion

7.Define a salt and give one example.

Ans: A salt is a compound formed when

when the hydrogen ions in an acid are replaced

by metal ions or by ammonium ions e.g. Barium

sulphate.

8.Name a salt that can be prepared

by precipitation

Ans: calcium sulphate: insoluble salt can be

prepared by precipitations.

9. work out the relative formula 

of the following

i) Ca(HCO3)2

Ans:40 + (2x1)+(2x12)+(6x16) = 162

ii) Al2(so4)3

Ans:(2x27)+(3x32)+(12x16) = 342

10. why are some metals used 

to make bells?

Ans: Metals Have the properties of malleable

and ductile(means flexible but strong and tough).

so these properties helps them to vibrate and ring.