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Class 10 Chemistry Chapter 18 Salts Test 7 | Punjab Board 2027
Grade 10 Chemistry chapter 18 Full unit Test Model Paper
Prepare for your board examinations with the Class 10 Chemistry Chapter 18: Salts Class Test 7, part of the Punjab Board 2027 Model Papers and chapter-wise test series. This full-unit test is designed according to the new Chemistry syllabus issued by PECTAA Punjab. Students can use this test to assess their understanding of Chapter 18, revise important concepts related to salts, and improve their preparation for the Class 10 Chemistry annual examination. Practise this Class 10 Chemistry full unit test to strengthen your subject knowledge and prepare effectively for the Punjab Board examinations 2027.
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PAPER NO.07
CHEMISTRY
CHAPTER
WISE
WISE
Roll No.(in Figures):(in Words):
Chapter 18:
Salts
Salts
OBJECTIVE TYPE
Maximum Marks: 12
Time Allowed : 15 Minutes
Time Allowed : 15 Minutes
ABCD
1ABCD
2ABCD
3ABCD
4ABCD
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5ABCD
6ABCD
7ABCD
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9ABCD
10ABCD
11ABCD
12ABCD
NOTE:Four possible answers A, B, C and D to each question are given. The choice which you think is correct, fill that circle in front of that question with Marker or Pen ink. Cutting or filling two or more circles will result in zero mark in that question.
Q1.12
1.Which base is not soluble in water?
(A) KOH(B) Mg(OH)2(C) NaOH(D) Na2CO3
2.The oppositely charged ions in a salt are bonded by:
(A) Covalent bond(B) Metallic bond(C) Hydrogen bond(D) Electrostatic forces
3.The three dimensional network structure formed by ions is called:
(A) Molecular structure(B) Crystal lattice(C) Covalent network(D) Ionic chain
4.The shape of the crystal of NaCl is:
(A) Cubic(B) Hexagonal(C) Rhombic(D) Trigonal
5.The melting points of ionic compounds are generally:
(A) Very low(B) Moderate(C) Very high(D) Zero
6.Ionic compounds serve as:
(A) Weak electrolytes(B) Non-electrolytes(C) Strong electrolytes(D) Neutral substances
7.Which salts are always soluble in water?
(A) Chlorides(B) Sulphates(C) Nitrates(D) Carbonates
8.Which carbonates are insoluble in water?
(A) Magnesium carbonates(B) Sodium carbonates(C) Ammonium carbonates(D) Potassium carbonates
9.Which salt will be formed when marble pieces react with dilute nitric acid?
(A) Sodium nitrate(B) Calcium nitrate(C) Potassium nitrate(D) Magnesium nitrate
10.Which of the following is insoluble in water?
(A) Sodium sulphate(B) Potassium sulphate(C) Barium sulphate(D) Magnesium sulphate
11.Water insoluble salt is:
(A) Calcium sulphate(B) Sodium sulphate(C) Potassium sulphate(D) Magnesium sulphate
12.Which of the following is prepared by reaction of Mg with H2SO4.
(A) MgCl2(B) MgCO3(C) MgSO4(D) Mg(NO3)2
Answers: 1-B 2-D 3-B 4-A 5-C 6-C 7-C 8-A 9-B 10-C 11-A 12-C
Q9: CaCO3 + 2HNO3 → Ca(NO3)2 + H2O + CO2↑ | Q12: Mg + H2SO4 → MgSO4 + H2↑
Q9: CaCO3 + 2HNO3 → Ca(NO3)2 + H2O + CO2↑ | Q12: Mg + H2SO4 → MgSO4 + H2↑
Here is Subjective Part of Paper.
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Roll No.(in Figures):(in Words):
Chapter 18:
Salts
Salts
SUBJECTIVE TYPE(PART – I)
Maximum Marks: 48
Time Allowed :1.45 Hours
Time Allowed :1.45 Hours
Q2.Write short answers to any FIVE (5) questions:(5×2=10)
(i)
Which factors are responsible for the strength of electrostatic forces between ions?
Ans: (1) Charge on the ions – higher charge gives stronger forces; (2) size of the ions – smaller ions give stronger forces.
(ii)
What is a salt?
Ans: An ionic compound formed when the hydrogen of an acid is replaced by a metal or by the NH4+ ion, e.g. NaCl.
(iii)
Is lead (II) chloride soluble in water? Give comments.
Ans: PbCl2 is only sparingly soluble in cold water, but it dissolves in hot water.
(iv)
What is a neutralization reaction?
Ans: The reaction of an acid with a base to form salt and water:
HCl + NaOH → NaCl + H2O
(v)
Which lead salts are insoluble in water?
Ans: Lead sulphate (PbSO4), lead carbonate (PbCO3) and lead chloride (PbCl2, in cold water).
(vi)
What is a crystal lattice?
Ans: The regular three-dimensional arrangement of ions in a solid ionic compound, held together by electrostatic forces.
(vii)
Name two insoluble carbonates.
Ans: Calcium carbonate (CaCO3) and magnesium carbonate (MgCO3).
(viii)
What shape is the crystal lattice of NaCℓ?
Ans: Cubic.
Q3.Write short answers to any FIVE (5) questions:(5×2=10)
(i)
Write down the formula of copper sulphate?
Ans: CuSO4 (crystals: CuSO4·5H2O).
(ii)
Write the equation for formation of sodium chloride.
Ans: 2Na + Cℓ2 → 2NaCℓ
Na → Na+ + e− ; Cℓ + e− → Cℓ− ; Na+ + Cℓ− → NaCℓ
(iii)
Why are melting points of ionic salts generally very high?
Ans: Strong electrostatic forces hold the ions in the lattice, so a large amount of heat energy is needed to break them.
(iv)
Why do ions with higher charges and smaller sizes have higher melting points?
Ans: Higher charge and smaller size make the attraction between ions stronger, so more energy is required to separate them.
(v)
Why ionic salts exist in solid state?
Ans: The strong forces of attraction keep the ions tightly bound in fixed positions, so they stay solid at room temperature.
(vi)
Why do ionic compounds do not conduct electricity in solid state?
Ans: In the solid state the ions are fixed in the lattice and are not free to move to carry charge.
(vii)
How will you prepare calcium sulphate in the laboratory?
Ans: By precipitation: mix solutions of calcium chloride and sodium sulphate, then filter, wash and dry the solid.
CaCℓ2 + Na2SO4 → CaSO4↓ + 2NaCℓ
(viii)
Which salts are always soluble in water?
Ans: All salts of sodium, potassium and ammonium, and all nitrates.
Q4.Write short answers to any FIVE (5) questions:(5×2=10)
(i)
Compare the melting points of NaCℓ and MgCℓ2.
Ans: NaCℓ melts at about 801 °C and MgCℓ2 at about 714 °C. (Check the values given in your own textbook.)
(ii)
What is the solubility rule for carbonates?
Ans: Carbonates are insoluble except those of Na+, K+ and NH4+.
(iii)
What is the solubility rule for hydroxides?
Ans: Hydroxides of Na+, K+ and NH4+ are soluble; Ca(OH)2 is slightly soluble; all others are insoluble.
(iv)
How would you prepare pure crystals of copper sulfate in the laboratory?
Ans: Warm dilute H2SO4 and add copper oxide until no more dissolves; filter off the excess, evaporate the filtrate to saturation, cool to get crystals, then dry them between filter papers.
CuO + H2SO4 → CuSO4 + H2O
(v)
Which lead salts are insoluble in water?
Ans: PbSO4, PbCO3 and PbCℓ2 (in cold water).
(vi)
Which calcium salt is soluble and which is insoluble?
Ans: Soluble: calcium nitrate, Ca(NO3)2. Insoluble: calcium carbonate, CaCO3.
(vii)
What is the titration method ?
Ans: A method of preparing soluble salts by reacting a soluble acid with a soluble base; an indicator shows the exact point of neutralization, and the salt is then crystallized.
(viii)
Which salts of barium are soluble in water?
Ans: Barium chloride (BaCℓ2) and barium nitrate (Ba(NO3)2).
(PART – II)
Note: Attempt any TWO questions.(2 × 9 = 18)
Q5.(a) Explain the formation of sodium chloride crystal?5
Ans: Sodium (2,8,1) loses one electron to form Na+; chlorine (2,8,7) gains one electron to form Cℓ−. Both get a stable noble-gas configuration.
Na → Na+ + e− | Cℓ + e− → Cℓ− | Na+ + Cℓ− → NaCℓ
The oppositely charged ions attract each other by electrostatic forces and pack into a cubic crystal lattice, each Na+ surrounded by six Cℓ− and vice versa.
(b) Explain the methods of preparation of two soluble salts.4
1. Titration method (NaCℓ): neutralize NaOH with HCl using an indicator, repeat without indicator, evaporate and crystallize.
NaOH + HCl → NaCℓ + H2O
2. Metal + acid (ZnSO4): add excess zinc to dilute H2SO4, filter off the excess zinc, evaporate and crystallize.
Zn + H2SO4 → ZnSO4 + H2↑
Q6.(a) Describe which salts are soluble in water and which are insoluble.5
Soluble: all salts of Na+, K+, NH4+; all nitrates; most chlorides (except AgCℓ, Hg2Cℓ2, PbCℓ2 in cold water); most sulphates (except BaSO4, PbSO4, CaSO4).
Insoluble: most carbonates (except Na+, K+, NH4+); most hydroxides (except Na+, K+, NH4+; Ca(OH)2 is slightly soluble).
Insoluble: most carbonates (except Na+, K+, NH4+); most hydroxides (except Na+, K+, NH4+; Ca(OH)2 is slightly soluble).
(b) Explain melting points of Ionic compounds.4
Ans: Ionic compounds have very high melting points because the ions are held in a lattice by strong electrostatic forces, and much heat energy is needed to overcome them. The melting point rises with higher ionic charge and smaller ionic size, because the attraction between ions becomes stronger.
Q7.(a) How will you prepare pure crystals of sodium sulphate in the laboratory?5
Ans (titration method):
- Put 25 cm3 of NaOH solution in a conical flask and add 2–3 drops of indicator.
- Add dilute H2SO4 from the burette until the colour just changes; note the volume.
- Repeat with the same volumes without indicator.
- Evaporate the solution to saturation, then cool to obtain crystals.
- Filter, wash and dry the crystals between filter papers.
(b) Why Ionic compound do not conduct electricity in solid state but in molten state and when dissolved in water they conduct electricity?4
Ans: In the solid state the ions are held in fixed positions in the lattice and cannot move. On melting, or on dissolving in water, the lattice breaks down and the ions become free to move, so they carry electric charge.
