CHEMISTRY MCQS WITH ANSWER by general knowledge Solutions

CHEMISTRY MCQS WITH ANSWER by general knowledge Solutions 

1. Which one of the following species contains an unpaired electron?  

• A N2
• B N2O 
• C NO2 
• D NO3– 
• E N2O4 

2. How does the volume of 1 mol of an ideal gas change if the temperature and the pressure are both decreased by a factor of four?  

• A decreases by four times  
• B decreases by sixteen times 
• C increases by four times 
• D increases by sixteen times 
• E remains unchanged 

3. Identify the INCORRECT statement below regarding chemical equilibrium. 

•  A All chemical reactions are, in principle, reversible. 
• B Equilibrium is achieved when the forward reaction rate equals the reverse reaction rate. 
• C Equilibrium is achieved when the concentrations of species become constant. 
• D Equilibrium is achieved when the reaction quotient, Q, equals the equilibrium constant.  
• E Equilibrium is achieved when reactant and product concentrations are equal. 

4. What happens when a catalyst is added to a system at equilibrium? 

• A The reaction follows an alternative pathway of lower activation energy. 
• B The heat of reaction decreases. C The potential energy of the reactants decreases. 
• D The potential energy of the products decreases. 
• E The rate of chemical reaction decreases. 

5. If the temperature is increased the amount of SO3(g) produced will:  

• A increase. 
• B decrease. 
• C remain the same

6. Which one of the following statements is not correct? 

• A Since voltage depends on concentrations, using standard conditions makes it easier to compare different electrochemical reactions. 
• B We have to measure the cell potential to obtain the difference in potential energy because the potential of half-reactions cannot be measured directly. 
• C The direction of a redox reaction can only be determined experimentally. 
• D Half-cell potentials for half-reactions are determined by combining the relevant half-cell with a standardised half-cell. 

7. Which one of the following statements regarding a catalyst is not correct? 

• A An enzyme is a catalyst that only binds certain substrates. 
• B An enzyme is a protein that is a highly efficient catalyst for one or more chemical reactions in a living system. 
• C Catalysts increase the rate of a reaction by altering the mechanism, thereby increasing the activation energy. 
• D Catalysts do not alter the equilibrium constant for a chemical reaction

8. Which one of the following substances will form strong hydrogen bonds? 

• A HCOOH 
• B CH3CN 
• C CCl4 
• D SiH4 
• E CH3OCH3 

9. Which force is most important in allowing ammonia, NH3, to dissolve in water?  

• A hydrogen bonding 
• B dipole-induced dipole 
• C ion-dipole  
• D dipole-dipole 
• E ionic 

10. What is the oxidation number of phosphorus in KH2PO4?  

• A –VI 
• B –II 
• C 0 
• D +V 
• E +VI 

11. Which one of the following species contains a polar covalent bond?  

• A oxygen 
• B carbon dioxide 
• C sodium chloride 
• D magnesium fluoride 
• E helium 

12. Which one of the following elements has valence electrons in the n = 3 shell?  

• A beryllium 
• B oxygen 
• C silicon 
• D neon E hydrogen 

13. Which one of the following species has the same electron configuration as  the Al3+ cation?  

• A F – 
• B Cl– 
• C S2– 
• D O– 
• E Mg+ 

14. Which one of the following pairs of atoms would form a non-polar covalent bond?  

• A C and O 
• B N and O 
• C Cl and Cl 
• D Na and Cl 
• E Ne and Ne  

15. How many bonding and non-bonding electron pairs are found in the BF3 molecule? 

• A 1 bonding and 3 non-bonding 
• B 2 bonding and 2 non-bonding 
• C 3 bonding and 1 non-bonding 
• D 3 bonding and 0 non-bonding  
• E 4 bonding and 0 non-bonding 

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