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Class 10 Chemistry Chapter 18 Salts Test 5 – Punjab Board 2027
Grade 10 Chemistry chapter 18 Topic Covered 18.1 to 18.3
Prepare for your matric Chemistry examination with the Class 10 Chemistry Chapter 18 Salts Class Test 5, part of the Punjab Board 2027 Model Papers and Chapter-Wise Test Series available at 786Times.com. This test covers textbook topics 18.1 to 18.3 from Chapter 18: Salts, according to the new syllabus issued by the Punjab Education, Curriculum, Training and Assessment Authority (PECTAA), Punjab. These Class 10 Chemistry chapter-wise tests help students revise important concepts, assess their subject knowledge, and strengthen their examination preparation. Practice this Chemistry test to improve your understanding of salts and prepare effectively for the Punjab Board Class 10 Chemistry examination. Visit 786Times.com for more chapter-wise tests, model papers, and educational resources based on the Punjab Board 2027 syllabus.
Chapter Wise Class TestT-5Chapter-18Salts
1.1 Choose the correct Answer.(Time: 7 Minutes)(Total Marks: 8)
1.Which of the following is an alkali?
(a) HCl(b) NaOH(c) NaCl(d) H2O
✔ Answer: (b) NaOH
2.Strength of electrostatic attraction depends on:
(a) Color of ions(b) Shape of ions(c) Charge and distance between ions(d) Temperature only
✔ Answer: (c) Charge and distance between ions
3.The structure of NaCl crystal is:
(a) Simple cube(b) Face-centered cube(c) Hexagonal(d) Linear
✔ Answer: (b) Face-centered cube
4.The past, used as a valuable currency.
(a) Water(b) Gold(c) Sugar(d) Salt
✔ Answer: (d) Salt
5.Ionic compounds usually have:
(a) Low melting points(b) Very high melting points(c) No melting point(d) Variable melting points like gases
✔ Answer: (b) Very high melting points
6.Which factor increases the melting point of an ionic compound?
(a) Larger ion size(b) Smaller ion size(c) Lower ionic charge(d) Weak attraction between ions
✔ Answer: (b) Smaller ion size
7.Ionic compounds do not conduct electricity in solid state because:
(a) They have no ions(b) Ions are not charged(c) Ions are not free to move(d) They contain water
✔ Answer: (c) Ions are not free to move
8.Ionic compounds conduct electricity in molten state because:
(a) They gain electrons(b) Ions become free to move(c) They become gases(d) They lose ions
✔ Answer: (b) Ions become free to move
786Times — Chemistry Chapter-18 Salts (T-5)
Chapter Wise Class TestT-5Chapter-18Salts
Total Marks: 17(Subjective Type)Time: 33 Minutes
2. Write short answers to any six (6) questions.[6 × 2 = 12]
(i)What is a neutralization reaction? Give an example.
Ans: The reaction of an acid with a base (alkali) to form a salt and water is called a neutralization reaction.
HCl + NaOH → NaCl + H2O
HCl + NaOH → NaCl + H2O
(ii)What factors affect the strength of ionic bonds?
Ans: The charges on the ions and the sizes of the ions (distance between them). Higher charges and smaller ions give a stronger ionic bond.
(iii)Where are sodium ions and chloride ions are located in NaCl crystal?
Ans: In the face-centered cubic lattice the Na+ and Cl− ions occupy alternate positions. Each Na+ ion is surrounded by six Cl− ions and each Cl− ion by six Na+ ions.
(iv)Why do ionic compounds have high melting points?
Ans: Oppositely charged ions in the giant lattice are held by very strong electrostatic forces. A large amount of energy is needed to break them.
(v)How Ionic charge and size affect melting point in Ionic compound.
Ans: Higher ionic charge and smaller ion size produce stronger attraction between ions, so the melting point is higher. Lower charge and larger size give a lower melting point.
(vi)Explain why MgO has a higher melting point than NaCl.
Ans: MgO has Mg2+ and O2− ions (charge 2+ and 2−) which are small, while NaCl has Na+ and Cl− (charge 1+ and 1−). So the attraction in MgO is much stronger and its melting point is higher.
(vii)Why do ionic compounds conduct electricity in molten state?
Ans: On melting, the lattice breaks down and the ions become free to move, so they can carry electric charge.
(viii)What is an electrolyte? Give an example.
Ans: A substance that conducts electricity in molten state or in aqueous solution and is decomposed by it. Example: NaCl.
(ix)Do you expect melting point of KCl to be higher or lower than NaCl?
Ans: Lower. The K+ ion is larger than Na+, so the attraction in KCl is weaker (KCl melts at about 770 °C, NaCl at about 801 °C).
Note: Attempt any one question.[5 × 1 = 5]
3.Explain the formation of sodium chloride crystal?
Ans: A sodium atom loses one electron and becomes Na+; a chlorine atom gains that electron and becomes Cl−.
Na → Na+ + e− Cl + e− → Cl−
The oppositely charged ions attract each other and arrange themselves in a regular face-centered cubic lattice. Each Na+ is surrounded by six Cl− and vice versa, forming a giant NaCl crystal.
Na → Na+ + e− Cl + e− → Cl−
The oppositely charged ions attract each other and arrange themselves in a regular face-centered cubic lattice. Each Na+ is surrounded by six Cl− and vice versa, forming a giant NaCl crystal.
4.Why melting points of ionic compounds are generally very high? Explain.
Ans: Ionic compounds have a giant lattice in which every ion is held by strong electrostatic forces of attraction to many oppositely charged neighbours. A large amount of heat energy is needed to overcome these forces, so melting points are very high. The melting point rises with higher ionic charge and smaller ion size (e.g. MgO melts higher than NaCl).
786Times — Chemistry Chapter-18 Salts (T-5)
