Chemistry MCQ with answer

1. A marine science student wighed out the components of a synthetic seawater solution using 3.02 g of NaCl, 0.0512 g of MgSO₄, 0.023 g CaCl₂ and 50.3 g of H₂O. What was the final mass of the solution (in g), stated to the correct number of significant figures.
   1. 53.3
   2. 53.39
   3. 53.4
   4. 53.3942
2. A 50.00 mL sample of a cough mixture prepared by a pharmacist was found to have a mass of 46.0 g. What is the density (in g/mL) of this mixture, stated to the correct number of significant figures.
   1. 0.92
   2. 0.920
   3. 0.9200
   4. 1.087
3. An atomic-level species is found to contain 16 protons, 16 neutrons and 18 electrons. This species is best described as
   1. an atom of sulphur (S)
   2. an isotope of sulphur
   3. a cation of sulphur
   4. an anion of sulphur
4. To study solubilities a solution of sodium hydroxide is added to a solution of each of the following compounds:

   (I)	silver nitrate	(III)	magnesium chloride
   (III)	potassium chloride	(IV)	lead nitrate

   Which one of the following would be observed?
   1. No precipitate would form in all cases
   2. A precipitate would form in all cases except (II)
   3. A precipitate would form in all cases except (II) and (III)
   4. A precipitate would form in all cases
5. Which one of the following pairs of elements would be expected to form an ionic compound when they combine?
   1. sulphur and oxygen
   2. phosphorus and oxygen
   3. magnesium and aluminium
   4. magnesium and sulphur
6. What is the correct formula for the compound sodium sulfite?
   1. Na₂SO₃
   2. Na₂SO₄
   3. Na₂S
   4. NaHSO₃
7. Which of the following processes involves only a physical change?
   1. Souring of milk
   2. Mixing an acid with a base
   3. Mixing a salt solution with water
   4. Mixing sodium with water
8. Consider the following elements: potassium (K); zinc (Zn); phosphorus (P); antimony (Sb); argon (Ar)
   Which of the following statements is true?
   
   1. All are metals
   2. All are non-metals
   3. All are chemically reactive
   4. One is a metalloid (semi-conductor)
9. The species contains
   1. 40 protons, 51 neutrons, 36 electrons
   2. 40 protons, 91 neutrons, 36 electrons
   3. 40 protons, 51 neutrons, 40 electrons
   4. 51 protons, 40 neutrons, 47 electrons
10. How many moles of hydrogen atoms are there in 0.5 mole of the compound CuSO₄.5H₂O?
    1. 0.5
    2. 2.5
    3. 5.0
    4. 10.0
    
    
    
    

Ans

1. 53.4
2. 0.920
3. an anion of sulphur
4. A precipitate would form in all cases except (II)
5. magnesium and sulphur
6. Na₂SO₃
7. _{Mixing a salt solution with water}
8. _{One is a metalloid (semi-conductor)}
9. _{40 protons, 51 neutrons, 36 electrons}
10. _5.0