Solving ICSE Class 10 Chemistry Previous Year Question Papers ICSE Class 10 Chemistry Question Paper 2019 is the best way to boost your preparation for the board exams.
ICSE Class 10 Chemistry Question Paper 2019 Solved
Time: 2 hours
Maximum Marks: 80
General Instructions:
- Answers to this Paper must be written on the paper provided separately.
- You will not be allowed to write during the first 15 minutes.
- This time is to be spent in reading the Question Paper.
- The time given at the head of this paper is the time allowed for writing the answers.
- Section I is compulsory. Attempt any four questions from Section II.
- The intended marks for questions or parts of questions are given in brackets [ ].
Section – I (40 MARKS)
(Attempt all questions from this Section)
Question 1.
(a) Choose the correct answer from the options given below: [5]
(i) An electrolyte which completely dissociates into ions is:
(A) Alcohol
(B) Carbonic acid
(C) Sucrose
(D) Sodium hydroxide
Answer:
(D) Sodium hydroxide
(ii) The most electronegative elementfrom the following elements is:
(A) Magnesium
(B) Chlorine
(C) Aluminium
(D) Sulphur
Answer:
(B) Chlorine
(iii) The reason for using Aluminium in the alloy duralumin is:
(A) Aluminium is brittle
(B) Aluminium gives strength
(C) Aluminium brings lightness
(D) Aluminium lowers melting point
Answer:
(C) Aluminium brings lightness
(iv) The drying agent used to dry HCl gas is :
(A) Conc. H2SO4
(B) ZnO
(C) Al2O3
(D) CaO
Answer:
(A) Conc. H2SO4
(v) A hydrocarbon which is a greenhouse gas is :
(A) Acetylene
(B) Ethylene
(C) Ethane
(D) Methane
Answer:
(D) Methane
(b) Fill in the blanks with the choices given in brackets : [5]
(i) Conversion of ethanol to ethene by the action of concentrated sulphuric acid is an example of ………………………… . (dehydration /dehydrogenation /dehydrohalogenation)
Answer:
dehydration
(ii) When sodium chloride is heated with concentrated sulphuric acid below 200°C, one of the products formed is ………………………… (sodium hydrogen sulphate / sodium sulphate / chlorine)
Answer:
sodium hydrogen sulphate
(iii) Ammonia reacts with excess chlorine to form ………………………… . (nitrogen /nitrogen trichloride /ammonium chloride)
Answer:
nitrogen trichloride
(iv) Substitution reactions are characteristic reactions of ………………………… (alkynes / alkenes / alkanes)
Answer:
alkanes
(v) In Period 3, the most metallic element is ………………………… (sodium /magnesium/aluminium)
Answer:
sodium
(c) Write a balanced chemical equation for each of the following reactions: [5]
(i) Reduction of copper (II) oxide by hydrogen.
(ii) Action of dilute sulphuric acid on sodium hydroxide.
(iii) Action of dilute sulphuric acid on zinc sulphide.
(iv) Ammonium hydroxide is added to ferrous sulphate solution.
(v) Chlorine gas is reacted with ethene.
Answer:
(i) CuO + H2 → Cu + H2O
(ii) 2NaOH + H2SO4 → Na2SO4 + 2H2O
(iii) ZnS + H2SO4 → ZnSO4 + H2S
(iv) FeSO4 + 2NH4OH → (NH4)2SO4 + Fe(OH)< sub>2↓
(v)
(d) State one observation for each of the following: [5]
(i) Concentrated nitric acid is reacted with sulphur.
Answer:
(ii) Ammonia gas is passed over heated copper (II) oxide.
Answer:
The black colour copper oxide will change to reddish pink copper.
(iii) Copper sulphate solution is electrolysed using copper electrodes.
Answer:
When copper sulphate solution is electrolysed using copper electrodes, reddish pink deposit of copper metal takes place on cathode.
(iv) A small piece of zinc is added to dilute hydrochloric acid.
Answer:
Zn + 2HCl → ZnCl2 + H2↑
Zinc metal dissolves forming solution with the liberation of hydrogen gas which bums with blue flame and gets extinguished with pop sound.
(v) Lead nitrate is heated strongly in a test tube.
Answer:
White powder of lead nitrate decompose to form yellow coloured lead oxide and liberating dense brown fumes of nitrogen dioxide gas.
(e) (i) Calculate: [5]
1. The number of moles in 12 g of oxygen gas. [O = 16]
2. The weight of 1022 atoms of carbon.
[C = 12, Avogadro’s No. = 6 × 1023]
Answer:
(i) 1. Oxygen gas (O2)
Molecular mass = 16 × 2 = 32 g
32 g of oxygen gas → 1 mole
1 g of oxygen gas → \(\frac{1}{32}\) mole
12 g of oxygen gas → \(\frac{1}{32}\) × 12 mole = 0.375 mole
2. 6.022 × 1023 atoms of carbon weigh → 12 g
1 atom of carbon weighs → \(\frac{12}{6 \times 10^{23}}\)
1022 atoms of carbon will weigh 12
→ \(\frac{12}{6 \times 10^{23}}\) × 1022 = \(\frac{12}{60}=\frac{1}{5}\) = 0.2 g
(ii) Molecular formula of a compound is C6H10O3 Find its empirical formula.
Answer:
Molecular formula = C6H18O3
Take the common multiple
Molecular formula = (C2H6O)3
Molecular formula= (Empirical formula)
Thus, empirical formula = C2H6O
(f) (i) Give the 1UPAC name of the following organic compounds: [5]
Answer:
1. Prop – 1 – yne or propyne
2. Ethanal
(ii) What is the specialfeature of the structure ofethyne?
Answer:
H — C ≡ C — H
Special feature of the structure of ethyne is the presence of triple bond.
(iii) Name the saturated hydrocarbon containing two carbon atoms.
Answer:
(iv) Give the structural formula ofAcetic acid.
Answer:
Acetic acid (CH3COOH)
(g) Give the appropriate term defined by the statements given below: [5]
(i) The formula that represents the simplest ratio of the various elements present in one molecule of the compound.
(ii) The substance that releases hydronium ion as the only positive ion when dissolved in water.
(iii) The tendency of an atom to attract electrons towards itself when combined in a covalent compound.
(iv) The process by which certain ores, specially carbonates, are converted to oxides in the absence of air.
(v) The covalent bond in which the electrons are shared equally between the combining atoms.
Answer:
(i) Empirical formula
(ii) Acid
(iii) Electronegativity
(iv) Calcination
(v) Non-polar covalent bond
(h) Arrange the following according to the instructions given in brackets: [5]
(i) K, Pb, Ca, Zn. (In the increasing order of the reactivity)
(ii) Mg2+, Cu2+, Na1+, H1+ (In the order of preferential discharge at the cathode)
(iii) Li, K, Na, H (In the decreasing order of their ionization potential)
(iv) F, B, N, O (In the increasing order of electron affinity)
(v) Ethane, methane, ethene, ethyne. (In the increasing order of the molecular weight) [H = 1, C = 12]
Answer:
(i) Pb < Zn < Ca < K
(According to the position in reactivity series)
(ii) Na1+ < Mg2+ < H1+ < Cu2+
(According to electrochemical series of metals)
(iii) H > Li > Na > K
(Smaller the size greater is the ionization potential)
(iv) B < N < O < F
(Smaller the size more is the electron affinity)
(v)
Section – II (40 Marks)
Attempt any four questions from this Section
Question 2.
(a) Draw the electron dot structure of: [3]
(i) Nitrogen molecule [N = 7]
(ii) Sodium chloride [Na = 11, Cl = 17]
(iii) Ammonium ion [N = 7, H = 1]
Answer:
(i) Nitrogen molecule
Nitrogen atom shares three electrons forming a triple covalent bond.
(ii) Sodium chloride
Sodium loses one electron to chlorine forming a positive ion and chlorine gains one electron forming a negative ion. These ions form an electrovalent bond and are held strongly by electrostatic forces of attraction.
(iii) Ammonium ion
Ammonia donates its lone pair to proton forming ammonium ion.
(b) The pH values of three solutions A, B and C are given in the table. Answer the following questions: [3]
| Solution | pH value |
| A | 12 |
| B | 2 |
| C | 7 |
(i) Which solution will have no effect on litmus solution ?
(ii) Which solution will liberate CO2 when reacted with sodium carbonate ?
(iii) Which solution will turn red litmus solution blue ?
Answer:
(i) C (Because pH 7 is neutral)
(ii) B (Because acids liberate CO2 gas when treated with carbonates and acids have pH less than 7)
(iii) A (Bases turn red litmus blue and they have pH more than 7)
(c) Study the extract of the Periodic Table given below and answer the questions that follow. Give the alphabet corresponding to the element in question. DO NOT repeat an element. [4]
(i) Which element forms electrovalent compound with G?
(ii) The ion of which element will migrate towards the cathode during electrolysis?
(iii) Which non-metallic element has the valency of 2 ?
(iv) Which is an inert gas ?
Answer:
(i)
(ii) A [Positive ions migrate towards cathode, hence A will form A+ and migrate towards cathode]
(iii) E
(iv) F
Question 3.
(a) Name the particles present in : [3]
(i) Strong electrolyte
(ii) Non-electrolyte
(iii) Weak electrolyte
Answer:
(i) Only ions
(ii) molecules
(iii) Ions as well as molecules
(b) Distinguish between the following pairs of compounds using the reagent given in the bracket. [3]
(i) Manganese dioxide and copper (II) oxide, (using concentrated HCl)
(ii) Ferrous sulphate solution and ferric sulphate solution, (using sodium hydroxide solution)
(iii) Dilute hydrochloric acid and dilute sulphuric acid, (using lead nitrate solution)
Answer:
(c) Choose the method ofpreparation of the following salts, from the methods given in the list: [4]
[List: A. Neutralization
B. Precipitation
C. Direct combination
D. Substitution]
(i) Lead chloride
(ii) Iron (II) sulphate
(iii) Sodium nitrate
(iv) Iron (III) chloride
Answer:
(i) Lead chloride → Precipitation(B)
(ii) Iron (II) sulphate → Substitution (D)
(iii) Sodium nitrate → Neutralisation (A)
(iv) Iron (III) chloride → (Direct combination) (C)
Question 4.
(a) Complete the following equations : [3]
(i) S + conc. HNO3 →
(ii) C + conc. H2SO4 →
(iii) Cu + dil.HNO3 →
Answer:
(i) S + 6HNO3 → H2SO4 + 6NO2 + 2H2O
(ii) C + 2H2SO4 → 2H2O + CO2 + 2SO2
(iii) 3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO + 4H2O
(b) Write a balanced chemical equation for the preparation of: [3]
(i) Ethene from bromoethane
(ii) Ethyne using calcium carbide
(iii) Methane from sodium acetate.
Answer:
(c) Name the following organic compounds : [4]
(i) The compound with 3 carbon atoms whose functional group is a carboxyl.
(ii) Thefirst homologue whose generalformula is CnH2n.
(iii) The compound that reacts with acetic acid to form ethyl ethanoate.
(iv) The compound formed by complete chlorination of ethyne.
Answer:
(i) propanone
(ii) ethene
(iii) ethanol
(iv) 1, 1, 2, 2 tetrachloro ethane
Question 5.
(a) Give the chemical formula of: [3]
(i) Bauxite
(ii) Cryolite
(iii) Sodium aluminate
Answer:
(i) Al2O3. 2H2O
(ii) Na3AlF6
(iii) NaAlO2
(b) Answer the following questions based on the extraction of aluminium from alumina by Hall-Heroult s Process : [3]
(i) What is the function of cryolite used along with alumina as the electrolyte ?
(ii) Why is powdered coke sprinkled on top of the electrolyte ?
(iii) Name the electrode, from which aluminium is collected.
Answer:
(i) Cryolite acts as a solvent and lower the fusion temperature from 2050°C to 950°C.
(ii) A layer of powdered coke is sprinkled over the surface of the electrolyte to reduce the heat loss by radiation and prevent the carbon rod from burning in air.
(iii) Cathode
(c) Match the alloys given in column I to the uses given in column II: [4]
| Column I | Column II |
| (i) Duralumin | A. Electrical fuse |
| (ii) Solder | B. Surgical instruments |
| (iii) Brass | C. Aircraft body |
| (iv) Stainless Steel | D. Decorative articles |
Answer:
(i) Duralumin → Aircraft body
(ii) Solder → Electrical fuse
(iii) Brass → Decorative articles
(iv) Stainless steel → Surgical instruments
Question 6.
(a) Identify the substances underlined: [3]
(i) The catalyst used to oxidise ammonia.
(ii) The organic compound which when solidified, forms an ice like mass.
(iii) The dilute acid which is an oxidizing agent.
Answer:
(i) Platinum
(ii) Acetic acid
(iii) Nitric acid
(b) Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation : [3]
2NaOH + CuSO4 → Na2So4 + Cu(OH)2↓
(i) What mass of copper hydroxide is precipitated by using 200 gm of sodium hydroxide ?
[H = 1, O = 16, Na = 23, S = 32, Cu = 64]
(ii) What is the colour of the precipitate formed?
Answer:
(i)
98 g of CU(OH)2 is precipitated by using 80 g of NaOH
1 g of CU(OH)2 is precipitated by using \(\frac{80}{98}\) g of NaOH
200 g of Cu(OH)2 is precipitated by using \(\frac{80}{98}\) × 200g
= 163.26 of NaOH
(ii) Pale blue precipitates
(c) Find the empirical formula and the molecular formula of an organic compound from the data given below:
C = 75.92%, H = 6.32% and N = 17.76%o
The vapour density of the compound is 39.5.
[C = 12, H = 1, N = 14] [4]
Answer:
Empirical Formula ⇒ C5H5
Vapour density = 39.5
Molecular Mass = 2 × V.D.
= 2 × 39.5 = 79
Empirical formula Mass
= 12 × 5 + 5 × 1 + 1 × 14
= 60 + 5 + 14 = 79
n = \(\frac{\text { Molecular formula mass }}{\text { Empirical formula mass }}\)
= \(\frac{79}{79}\) = 1
Thus, both Empirical formula and Molecular formula are C5H5N.
Question 7
(a) Name the gas evolved in each of the following cases : [3]
(i) Alumina undergoes electrolytic reduction.
(ii) Ethene undergoes hydrogenation reaction.
(iii) Ammonia reacts with heated copper oxide.
Answer:
(i) Oxygen
(ii) Ethane
(iii) Nitrogen
(b) Study the flow chart given and give balanced equations to represent the reactions A, B and C. [3]
Answer:
(A) Mg3N2 + 6H20 → 3Mg(OH)2 + 2NH3
(B) NH3 + HCl → NH4Cl
(C)
(c) Copy and complete the following table which refers to the industrial method for the preparation of ammonia and sulphuric acid: [4]
Answer:
