Kerala SSLC · Chemistry · Class 10
Reactivity Series and Electrochemistry: Important Questions with Answers
These are 10 important multiple-choice questions from the Kerala SSLC Chemistry chapter “Reactivity Series and Electrochemistry” (Kerala SCERT syllabus). Each one shows the correct answer and a short explanation of why it is right. Try answering before you read the answer. ExamSummary has 10 practice questions on this chapter in total.
Q1.Which of the following metals is the most reactive according to the standard reactivity series?
- A)Iron
- B)Copper
- C)Potassium
- D)Silver
Answer: C) Potassium
Potassium is located at the top of the reactivity series among the given options. It loses electrons most easily compared to iron, copper, or silver. Therefore, it reacts vigorously with water and acids.
Q2.When an iron nail is dipped into a copper sulphate solution, what observation is made?
- A)No change occurs in the solution.
- B)The solution turns green and reddish-brown copper deposits.
- C)The iron nail dissolves completely leaving a clear solution.
- D)The solution turns blue and iron precipitates out.
Answer: B) The solution turns green and reddish-brown copper deposits.
Iron is more reactive than copper, so it displaces copper from the copper sulphate solution. This forms ferrous sulphate, which is green, and elemental copper, which deposits as a reddish-brown solid.
Q3.Highly reactive metals like aluminium are extracted from their ores by which process?
- A)Heating with carbon
- B)Reduction with hydrogen
- C)Electrolytic reduction
- D)Simple heating alone
Answer: C) Electrolytic reduction
Highly reactive metals form very stable compounds that cannot be reduced by carbon or heat. Electrolytic reduction uses electric current to break these strong bonds and extract the pure metal.
Q4.Why is hydrogen included in the reactivity series of metals?
- A)Because it is a gas at room temperature.
- B)To compare its ability to lose electrons with metals.
- C)Because it reacts with all metals.
- D)To act as a catalyst in reactions.
Answer: B) To compare its ability to lose electrons with metals.
Hydrogen is placed in the series to serve as a reference point for comparing the reactivity of metals. Metals above hydrogen can displace it from acids, while those below cannot.
Q5.In an electrolytic cell, the electrode connected to the positive terminal of the battery is called the:
- A)Cathode
- B)Anode
- C)Electrolyte
- D)Salt bridge
Answer: B) Anode
The anode is the positive electrode in an electrolytic cell where oxidation occurs. It attracts negative ions (anions) from the electrolyte to undergo chemical change.
Q6.During electroplating of a spoon with silver, the spoon acts as the:
- A)Anode
- B)Cathode
- C)Electrolyte
- D)Power source
Answer: B) Cathode
In electroplating, the object to be coated is made the cathode to attract positively charged metal ions. Silver ions gain electrons at the cathode surface and deposit as solid silver.
Q7.In a galvanic cell, electrons flow through the external wire from:
- A)Cathode to Anode
- B)Anode to Cathode
- C)Positive to Negative Terminal only
- D)Electrolyte to Electrodes
Answer: B) Anode to Cathode
Oxidation occurs at the anode, releasing electrons which then travel through the external circuit. These electrons move towards the cathode where reduction takes place.
Q8.Solid sodium chloride does not conduct electricity, but molten sodium chloride does because:
- A)It contains free-moving electrons.
- B)Ions become mobile only when melted or dissolved.
- C)Heat creates new electrons in the solid.
- D)The crystal structure remains intact in liquid.
Answer: B) Ions become mobile only when melted or dissolved.
In solid state, ions are fixed in a lattice and cannot move to carry charge. When molten, the lattice breaks down allowing ions to move freely and conduct electricity.
Q9.Sodium metal is stored under kerosene oil primarily to prevent:
- A)Reaction with oxygen and moisture in air.
- B)Evaporation of the metal itself.
- C)Freezing due to low temperatures.
- D)Oxidation by nitrogen gas.
Answer: A) Reaction with oxygen and moisture in air.
Sodium is extremely reactive and catches fire upon contact with moisture or oxygen in the air. Kerosene oil acts as a barrier preventing these dangerous reactions.
Q10.Which method is commonly used to protect iron pipes from rusting by coating them with zinc?
- A)Painting
- B)Galvanization
- C)Annealing
- D)Tempering
Answer: B) Galvanization
Galvanization involves coating iron with a layer of zinc to prevent corrosion. Zinc acts as a sacrificial protector because it is more reactive than iron and corrodes first.