JHS 2 Science Questions

 

JHS 2 Science Questions

Section A - Objectives

1. When a substance is made of the same kind of atoms it is called

A. A mixture

B. A compound  

C. An element

D. A solution

 

2. In the nucleus of an atom, there are

A. neutrons and shells

B. Protons and electrons

C. neutrons and protons

D. electrons and shells

 

3. How many electrons are needed to equal the mass of 1 proton?

A. About 1000

B. About 1500

C. about 1800

D. About 2000

 

4. A neutral atom has five protons and five neutrons in its nucleus. How many electrons are present in the atom?

A. 2

B. 3

C. 4

D. 5

 

5. Atoms of the same element have the same

I. number of electrons

II. number of protons

III. chemical properties

A.    I and II only  

B.     I and III only

C.     II and III only

D.    I, II and III

6. Which of the following elements is a noble gas?

A. argon

B. Oxygen

C. Hydrogen

D. Nitrogen

 

7. The chemical formula H₂ represents

A. Two atoms of hydrogen

B. neutrons of hydrogen

C. Two ions of hydrogen

D. two molecules of hydrogen

 

8. The combining power of an element is called

A. Reduction

B. Oxidation

C. Valency

D. Electronegativity

 

9. Atoms of a particular kind of element that have the same atomic number, but different masses are termed

A. Noble gases

B. Compounds

C. Isotopes

D. Radicals

 

10. An atom of sodium has 11 Peters, 11 electrons and a mass number of 23. What is the total electric charge of the atom?

A. 23

B. 22

C. 11

D. 0

 

Section B – Essay

1.    (a) Determine the oxidation state of copper in the following compounds:

(i)                 CuCl₂

(ii)              CuSO₄

(iii)            Cu (NO₃)₂

 

(b) Balance the following chemical equations:

       (i) K + H₂O à KOH + H₂

        (ii) N₂ + H₂ à NH₃

             (iii) H₂ + O₂ à H₂O

 

  (c) state two differences each between:

       (i.) a cation and an anion

       (ii) an atom and an ion

 

  (d) List the ions of the following radicals:

        (i) Ammonium        (ii) Permanganate

 

2.      (a) Define an atom?

 

(b) Complete the table below by filling in the empty spaces.

 

Subatomic particle	Charge	Mass	Location
Electron			Outside the nucleus
Proton
Neutron

 

          (c)  Give one reason why atoms are electrically neutral.

           (d) Distinguish between the following pairs of terms:

                  (i) atomic number in mass number

                  (ii) Atomic mass and atomic weight

(e) Give the names of the products formed when the following pairs of compounds react together:

    (i) NH₄OH and dilute HCl

    (ii) CaCO₃ and dilute HCl

Hint: Y2T1