Elements of Group 1 and 2 — Class 11 MCQs with Answers
Class 11 CBSE Chemistry · Chapter 303
40 practice questions · 20 Easy · 20 Medium · Updated
Practise the most important Class 11 CBSE Chemistry questions from Chapter 303, "Elements of Group 1 and 2". You get 4 timed quizzes made from 40 NCERT-based MCQs, with answers and explanations. The questions are split into 20 Easy and 20 Medium. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG apart.
To score well in "Elements of Group 1 and 2", focus on reactions, key concepts and careful numericals. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Elements of Group 1 and 2, then move to Medium to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 11 Chemistry mastery score. 6 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Elements of Group 1 and 2 (Class 11 Chemistry)
The s-block holds the two most reactive families of metals: the alkali metals of group 1 (Li, Na, K, Rb, Cs) with an ns¹ configuration, and the alkaline earth metals of group 2 (Be, Mg, Ca, Sr, Ba) with ns². Because the valence electrons are few and loosely held, almost everything in this chapter follows from a single chain of reasoning — size increases down a group, ionisation enthalpy and hydration enthalpy fall, and reactivity therefore rises. Layered on top of that smooth trend are two exceptions worth memorising, the anomalous behaviour of lithium and beryllium and their diagonal relationships with magnesium and aluminium, followed by the industrial chemistry of NaOH, Na₂CO₃, NaHCO₃, CaO, Ca(OH)₂, CaCO₃ and plaster of Paris, and the biological roles of Na, K, Mg and Ca.
- Electronic configuration of the s-block
- Alkali metals have the valence configuration ns¹ and alkaline earth metals ns², both sitting just after a noble gas core. Losing these one or two electrons gives M⁺ or M²⁺ with a noble gas arrangement, which is why the +1 and +2 states are the only ones normally seen.
- Atomic and ionic radii
- Radii increase down each group as a fresh shell is added, so Li < Na < K < Rb < Cs and Be < Mg < Ca < Sr < Ba. Across a period, a group 2 atom is smaller than its group 1 neighbour because the extra nuclear charge pulls the same shell inwards; the cation is always much smaller than the parent atom.
- Ionisation enthalpy
- Alkali metals have the lowest first ionisation enthalpy in their periods and the value falls further down the group as the valence electron moves away from the nucleus and is better shielded. The second ionisation enthalpy of an alkali metal is enormous because it would break into the noble gas core, which is why M²⁺ is never formed.
- Hydration enthalpy
- Smaller ions attract water molecules more strongly, so hydration enthalpy follows Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺ and Be²⁺ > Mg²⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺. Li⁺ therefore carries the thickest water sheath, giving it the largest hydrated radius and the lowest ionic mobility in solution even though it is the smallest bare ion.
Elements of Group 1 and 2 — important questions & MCQs with answers (Class 11 Chemistry)
6 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 34 are timed and scored when you sign in.
- Q1Easy
The general valence shell electronic configuration of the alkali metals is
A.ns²np¹B.ns²np³C.ns¹✓ CorrectD.ns²Answer: C. ns¹
Explanation: Group 1 elements carry a single electron in the outermost s orbital, so the valence configuration is ns¹; losing that electron gives the stable noble-gas-like M⁺ ion.
- Q2Easy
The colour imparted to a Bunsen flame by sodium salts is
A.golden yellow✓ CorrectB.lilacC.apple greenD.crimson redAnswer: A. golden yellow
Explanation: The loosely held valence electron of sodium is excited by the flame and emits golden yellow light as it drops back to the ground state.
- Q3Easy
Lithium shows a diagonal relationship with
A.aluminiumB.calciumC.berylliumD.magnesium✓ CorrectAnswer: D. magnesium
Explanation: Li and Mg have closely similar sizes and charge-to-radius ratios, so both combine directly with nitrogen and both give the oxide when their nitrates are heated.
- Q4Medium
Among the alkali metal ions, the one with the highest hydration enthalpy is
A.K⁺B.Cs⁺C.Li⁺✓ CorrectD.Na⁺Answer: C. Li⁺
Explanation: Hydration enthalpy falls as ionic size grows; Li⁺ is the smallest ion, holds water molecules most strongly and therefore has the largest hydration enthalpy.
- Q5Medium
2.3 g of sodium reacts completely with water. The volume of hydrogen liberated, measured at 273 K and 1 atm (molar volume 22.4 L), is
A.1.12 L✓ CorrectB.2.24 LC.4.48 LD.0.56 LAnswer: A. 1.12 L
Explanation: 2.3 g of Na is 0.1 mol; from 2Na + 2H₂O → 2NaOH + H₂, 0.1 mol Na gives 0.05 mol H₂, which occupies 0.05 × 22.4 = 1.12 L.
- Q6Medium
On strong heating, lithium nitrate gives
A.Li and NO₂B.LiOH and NO₂C.LiNO₂ and O₂D.Li₂O, NO₂ and O₂✓ CorrectAnswer: D. Li₂O, NO₂ and O₂
Explanation: Unlike the other alkali metal nitrates, which give nitrites and oxygen, LiNO₃ behaves like Mg(NO₃)₂ and decomposes to the oxide, nitrogen dioxide and oxygen.
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Start this chapter free →Elements of Group 1 and 2 — FAQs
What are the key concepts in Class 11 Chemistry Elements of Group 1 and 2?+
The s-block holds the two most reactive families of metals: the alkali metals of group 1 (Li, Na, K, Rb, Cs) with an ns¹ configuration, and the alkaline earth metals of group 2 (Be, Mg, Ca, Sr, Ba) with ns². Because the valence electrons are few and loosely held, almost everything in this chapter follows from a single chain of reasoning — size increases down a group, ionisation enthalpy and hydration enthalpy fall, and reactivity therefore rises. Layered on top of that smooth trend are two exceptions worth memorising, the anomalous behaviour of lithium and beryllium and their diagonal relationships with magnesium and aluminium, followed by the industrial chemistry of NaOH, Na₂CO₃, NaHCO₃, CaO, Ca(OH)₂, CaCO₃ and plaster of Paris, and the biological roles of Na, K, Mg and Ca. Key ideas include Electronic configuration of the s-block, Atomic and ionic radii, Ionisation enthalpy, Hydration enthalpy.
What does Class 11 Chemistry Chapter 303 (Elements of Group 1 and 2) cover on XamBaaz?+
It has 40 NCERT-based MCQs on "Elements of Group 1 and 2": 20 Easy and 20 Medium. Together they make 4 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG.
Are these "Elements of Group 1 and 2" questions free to practise?+
Yes. Sign in with Google to practise "Elements of Group 1 and 2" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Elements of Group 1 and 2" for the exam?+
Start with the Easy quiz to check your basics, then try Medium to practise applying them. There are 4 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Elements of Group 1 and 2" MCQs available with answers?+
Yes. 6 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Elements of Group 1 and 2" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as JEE Main, JEE Advanced and NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Elements of Group 1 and 2 (Class 11 Chemistry)?+
The questions that matter most test Electronic configuration of the s-block, Atomic and ionic radii, Ionisation enthalpy, Hydration enthalpy. This page shows 6 solved important MCQs with answers and explanations; all 40 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Elements of Group 1 and 2?+
Yes — Class 11 Chemistry Elements of Group 1 and 2 has timed online quizzes at Easy and Medium levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.