Vidaara.orgClass 11 · Chemistry
CodeVID-C11-10-T3-01
Biological Importance & Anomalies — Assignment
Name: ____________________
Roll No.: __________
Date: ____________
General Instructions
- All questions are compulsory.
- Section A carries 1 mark each, Section B 2 marks, Section C 3 marks and Section D 5 marks.
- Show full working for Sections B, C and D; only final answers are provided.
Section A — Multiple Choice Questions
5 × 1 = 5 marks
1.
The ion concentrated mainly outside cells is:
- A.K+
- B.Na+
- C.Mg2+
- D.Ca2+
2.
Chlorophyll contains the ion:
- A.Ca2+
- B.Mg2+
- C.Na+
- D.K+
3.
The diagonal relationship is shown by:
- A.Na and Mg
- B.Li and Mg
- C.K and Ca
- D.Be and Mg
4.
Group 2 metals, compared with Group 1 of the same period, are:
- A.softer
- B.more reactive
- C.harder
- D.larger
5.
The ion essential for blood clotting is:
- A.Na+
- B.K+
- C.Ca2+
- D.Li+
Section B — Short Answer (2 marks)
3 × 2 = 6 marks
6.
State two biological functions of calcium.
7.
Why are the carbonates and sulphates of Group 2 less soluble than those of Group 1?
8.
Give one shared property of Li and Mg.
Section C — Long Answer (3 marks)
2 × 3 = 6 marks
9.
Explain the biological importance of sodium and potassium ions.
10.
Why do diagonal relationships arise in the periodic table? Illustrate with Li–Mg.
Section D — Detailed Answer (5 marks)
1 × 5 = 5 marks
11.
Summarise the similarities and differences between Group 1 and Group 2 metals, and explain the anomalous behaviour of their first members and the resulting diagonal relationships.
Answer Key
Section A — Multiple Choice Questions
- (B) Na+
- (B) Mg2+
- (B) Li and Mg
- (C) harder
- (C) Ca2+
Section B — Short Answer (2 marks)
- Building bones and teeth (as calcium phosphate/carbonate) and enabling blood clotting, muscle contraction and nerve signal transmission.
- The +2 charge on Group 2 ions gives much stronger lattice energies, so salts like CaCO3 and BaSO4 are far less soluble than the corresponding +1 Group 1 salts.
- Both react directly with nitrogen to form nitrides (Li3N, Mg3N2); their carbonates are also sparingly soluble.
Section C — Long Answer (3 marks)
- Na+ (outside cells) and K+ (inside cells) are kept apart by the ATP-driven Na–K pump. The resulting ion gradients transmit nerve impulses, regulate fluid balance and blood pressure, and control the entry of glucose and amino acids into cells.
- Moving one group right raises the charge while moving one period down raises the size; the two effects roughly cancel, giving similar charge-to-radius ratios. Thus Li+ and Mg2+ behave similarly — both form nitrides and sparingly soluble carbonates.
Section D — Detailed Answer (5 marks)
- Both are reactive s-block reducing metals forming ionic compounds (except the first members) and never found free. Group 1 (ns1, +1) is larger, softer, more reactive with lower ionisation enthalpy; Group 2 (ns2, +2) is smaller, harder, less reactive with higher ionisation enthalpy and less soluble salts. Li and Be are anomalous due to very small size and high charge density, giving covalent character. This same factor produces the diagonal relationships Li–Mg (nitrides, sparingly soluble carbonates) and Be–Al (amphoteric oxides, covalent chlorides).
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