Free Reactions of Group I Elements MCQs with Answers
68 Reactions of Group I Elements MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Group I elements have one valence electron, so their reactivity increases down the group as ionisation energy decreases. Their reactions with water, oxygen, hydrogen and halogens produce hydroxides, oxides, hydrides and halides, while the behaviour of lithium differs from the heavier metals because of its small ionic size.
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- A. decreases, because atomic radius increases
- B. stays constant
- C. decreases, because ionisation energy falls
- D. increases, because the outer electron is further from the nucleus and more easily lost
Explanation: Each element down the group has an extra shell, so the single outer electron is further from the nucleus and better shielded, ionisation…
Correct answer: increases, because the outer electron is further from the nucleus and more easily lost- A. are found free in nature
- B. react with water to form hydroxides that are strongly basic
- C. are all radioactive
- D. form acidic oxides
Explanation: Sodium and its neighbours react with water to give hydrogen and a hydroxide solution that is strongly alkaline, which is the origin of the…
Correct answer: react with water to form hydroxides that are strongly basic- A. sodium oxide, Na2O
- B. sodium superoxide, NaO2
- C. sodium peroxide, Na2O2
- D. sodium hydroxide, NaOH
Explanation: Lithium forms the simple oxide, sodium forms mainly the peroxide and potassium, rubidium and caesium form superoxides, the larger cations…
Correct answer: sodium peroxide, Na2O2- A. golden yellow
- B. brick red
- C. apple green
- D. lilac
Explanation: Heating excites the outer electron to a higher level and the colour is emitted as it falls back, the energy gap being characteristic of…
Correct answer: lilac- A. Light brown
- B. Light green
- C. Light Blue
- D. Light yellow
Explanation: Silver bromide forms a pale cream or light-yellow precipitate when bromide ions react with silver ions, so light yellow is the closest…
Correct answer: Light yellow- A. used as mordant in dyeing
- B. used in photography and medicines
- C. used in making green pigments
- D. All of these
Explanation: Silver nitrate is widely used in photography because light converts silver halides into metallic silver, and it is also used medicinally…
Correct answer: used in photography and medicines- A. Blue Stone
- B. Blue Vitriol
- C. Lunar Caustic
- D. Both A & B
Explanation: Silver nitrate is called lunar caustic because it is a corrosive silver salt that was historically associated with the moon and silver.
Correct answer: Lunar Caustic- A. AgNO
- B. AgNO2
- C. AgNO3
- D. AgNO4
Explanation: Silver forms Ag+ and nitrate is NO3−, so charge balance gives the formula AgNO3.
Correct answer: AgNO3- A. alcohol
- B. carbon dioxide
- C. chlorine
- D. sodium chlorine
Explanation: Chlorine is widely used as a bleaching agent because it forms hypochlorous acid in water, which releases reactive oxygen species that…
Correct answer: chlorine- A. NaOH
- B. KOH
- C. NaCl
- D. NaBH4
Explanation: Potash refers to potassium compounds, and caustic potash is potassium hydroxide, KOH. Sodium hydroxide, NaOH, is called caustic soda.
Correct answer: KOH- A. being s-block elements
- B. inert gas configurations
- C. ns1 electronic configuration
- D. being metals
Explanation: An alkali metal has the outer configuration ns1, so removal of its first electron produces a stable noble-gas configuration.
Correct answer: inert gas configurations- A. Lithium
- B. Sodium
- C. Potassium
- D. Rubidium
Explanation: Lithium reacts with oxygen mainly to form the normal oxide, Li2O. The larger alkali metals form peroxides or superoxides because their…
Correct answer: Lithium- A. Water
- B. HCI
- C. Na+
- D. NaCl
Explanation: At the cathode of a diaphragm cell, water is reduced more readily than sodium ions: 2H2O + 2e− → H2 + 2OH−.
Correct answer: Water- A. Na K
- B. Mg Ca
- C. Li Na
- D. Li Ca
Explanation: Lithium nitrate decomposes on heating to lithium oxide, nitrogen dioxide and oxygen: 4LiNO3 → 2Li2O + 4NO2 + O2.
Correct answer: Li Na- A. Base
- B. Basic salt
- C. Ashes
- D. Spirit
Explanation: The term alkali comes from an Arabic word referring to the ashes of plants, from which alkaline substances such as carbonates were…
Correct answer: Ashes- A. LiOH
- B. NaOH
- C. KOH
- D. CsOH
Explanation: LiOH has the greatest covalent character among the alkali-metal hydroxides because the small Li+ ion strongly polarizes OH−.
Correct answer: LiOH- A. sodium
- B. hydrogen
- C. chlorine
- D. oxygen
Explanation: In dilute aqueous sodium chloride, water is preferentially oxidized at the anode: 2H2O → O2 + 4H+ + 4e−.
Correct answer: oxygen- A. It corrodes the organic tissues
- B. It is used in soda water
- C. It reacts with chlorine gas
- D. It reacts with fats to form soap
Explanation: Sodium hydroxide is called caustic soda because it is strongly corrosive and can chemically burn organic tissues.
Correct answer: It corrodes the organic tissues- A. Hydroxide ions to reach anode
- B. Chlorine gas to mix
- C. Cathode to decay
- D. All of the above
Explanation: In a diaphragm cell, the anode compartment is kept at a slightly higher liquid level so brine flows towards the cathode compartment.
Correct answer: Hydroxide ions to reach anode- A. Water
- B. NaCl
- C. Aqueous sodium hydroxide
- D. H2SO4
Explanation: Heating ammonium chloride with aqueous sodium hydroxide gives ammonia, water and sodium chloride: NH4Cl + NaOH → NH3 + H2O + NaCl.
Correct answer: Aqueous sodium hydroxideReactions of Group I Elements MCQs: common questions
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