339716966-1st-year-chemistry-all-mcqs-short-questions-for-federal-board-punjab-board.docx

ARMY PUBLIC SCHOOL AND COLLEGE KOHAT CHEMISTRY – HSSC 1 ALL CHAPTERS MCQS AND SHORT QUESTIONS

1)

When an electron is added to a unipositive ion we get (a)anion (b) cation (c)neutral atom (d)molecule

2)

CO+ is an example of: (a)free radical (c) an ionic molecular ion

(b)cationic molecular ion (d)stable molecule

3)

Formula that gives us information about the simplest ratio of atoms in compound (a) structural formula (b) molecular formula (c) empirical formula (d) molar ratio

4)

Percentage of oxygen in H2O is (a) 80% (c) 8.8%

(b) 88.8% (d) 9.8%

5)

When 0.01 kg of CaCO3 is decomposed the CO2 produced occupies a volume at S.T.P. (a) 2.2414 dm3 (b) 22.414 dm3 (c) 22414 dm3 (d) 224014 dm3

6)

The no. of covalent bond in 10gm of NH3 are (a)6.022 x 1023 (c)10.62 x 1024

7)

No. of molecules present in 10gm of water are (a)3.37 x 1023 (c)3.37 x 1024

(b) 1.062 x 1023 (d) 1.062 x 1024

(b) 33.7 x 1023 (d) 3. 7 x 1024

8)

The no. of covalent bonds present in 10gm of water are (a) 6.074 x 1023 (b) 6.74 x 1023 (c) 6.074 x 1024 (d) 6.74 x 1024

9)

500 cm3 of H2 gas at STP contradictions of hydrogen (a)6.02 x 1023 (b) 3.01 x 1022 (c)2.68 x 1022 (d) 1.34 x 1022

10) The number of moles of CO2 which contains 8.0 gm of oxygen (a)0.25 (b) 0.50 (c)1.0 (d) 1.50 11) 27 grams of Al will react completely with how much mass of O2 to produce Al2O3 (a)8 gm of oxygen (b)16 gm of oxygen (c)32 gm of oxygen (d) 24 gm of oxygen 12)

13)

The mass of one mole of electron is (a)1.008 mg (c)1.673 mg

(b) 0.184 mg (d) 0.55 mg

The volume occupied by 1.4 gm of N2 at STP is (a)224 dm3

(b) 22.4 dm3

(c)1.12 dm3

(d) 112 cm3

14)

The order of the rate of diffusion of gases NH3, SO2, Cl2 and CO2 is (a)NH3 > SO2 > Cl2 > CO2 (b) NH3 > CO2 > SO2 > Cl2 (c) Cl2> SO2 > CO2 > NH3 (d) None of these

15)

If absolute T of a gas is doubled and the pressure is reduced to one half the volume of gas (a) remain unchanged (b) increases four times (c) reduce to half (d) be double

16) At high temperature isotherm moves away from both the axis because of increase in, (a) pressure (b) volume (c) no. of moles (d) all above 17) Values of Charle’s law constant K depends upon. (a) mass of gas (c)no. of moles of gas

(b)pressure gas (d)all above

18) Equal volumes of H2 and He are inserted in the same vessel. The P exerted are in the ratio: (a) 1:1 (b) 2:1 (c) 1:2 (d) all above 19) If absolute temperature is doubled and the pressure is increased 4 times. The volume is (a) half (b) double (c) four times (d) remains the changed 20) Density of a gas is usually expressed in (a) kg m3 (c)g dm-3 21) Units of gas constant R in SI system is: (a) 0.0821 dm3 atm k-1 mol-1 (c) 8.31 Nm k-1 mol-1

(b) kg dm3 (d) g cm-3

(b) 82.1 cm3 atm k-1 (d) 1.987 cal k-1 mol-1

22) Concept of distribution of velocities among the gas molecules was developed by (a)Claudius (b)Maxwell (c)Boltzman (d)Vanderwaal 23) A real gas obeying Vander Waal’s equation will resemble ideal gas if: (a) both ‘a’ and ‘b’ are large (b) both ‘a’ and ‘b’ are small (c) ‘a’ is small and ‘b’ is large (d) ‘a’ is large and ‘b’ is small 24) Deep sea divers breath mixture of nitrogen and oxygen in a ratio of: (a)96% N2 and 4% O2 (b)4% and N2 and 96% O2 (c)80% N2 and 20% O2 (d) 20% N2 and 80% O2 25)

In zero order reaction, the rate is independent of (a) temperature of reaction b) concentration of reactants (c)concentration of products (d) none of above

26)

The rate of reaction (a)increases as the reaction proceeds (c)remains the same as the reaction proceeds

(b) decreases as the reaction proceeds (d) may decrease or increase

27)

The unit of the rate constant is the same as that of the rate of reaction in (a)first order reaction (b) second order reaction (c)zero order reaction (d) third order reaction

28)

The unit of reaction is

(a)mole/dm3 (c)mole/dm3 sec

(b) mole/pound (d) mole/cm3

29)

The rate of reaction between two specific time intervals is called (a)instantaneous rate (b) average rate (c)specific rate (d) ordinary rate

30)

The sum of exponents of the conc. terms in the rate equation is called (a)rate of reaction (b) order of reaction (c)specific rate constant (d) average rate

31)

The average rate and instantaneous rate of a reaction are equal (a)at the start (b) at the end (c)in the middle (d) when 2 rate have time interval = zero

32) Photochemical reactions usually have order (a)one (c)two 33)

34)

The decomposition of ozone has order (a)first (c)second

(b) zero (d) three

(b) negative (d) pseudo first order

When a reaction occurs in many steps then the slowest step is the (a)main step (b) enthalpy determining step (c)mechanism determining step (d) rate determining step

35) The substance which retard the rate of chemical reaction (a)catalyst (b) inhibitor (c)auto catalyst (d) enzyme 36) The factors which affect rate of reaction (a)nature of reactants (c)light

(b) surface area (d) all of above

37)

Electrolysis is the process in which a chemical reaction takes place at the expense of (a) chemical energy (b) electrical energy (c) heat energy (d) none of these

38)

The oxidation number of chromium in K2Cr2O7 is (a)14 (b) 12 (c)6 (d) none of these

39)

In the reaction 2 Fe + Cl2 ( 2FeCl3 (a) Fe is reduced (c) Cl2 is oxidized

(b) Fe is oxidized (d) none of these

When aqueous solution of NaCl is electrolysed (a) Cl2 is evolved at the cathode (c) Na is deposited at the cathode

(b) H2 is evolved at cathode (d) Na appears at the anode

40)

41) Which one of the following will be good conductor of electricity (a) pure distilled water (b) molten NaCl (c) dilute solution of glucose (d) chloroform 42) During a redox reaction, an oxidizing agent (a) gains electrons (c) loses electrons 43) A oxidizing agent is a substance which brings about

(b) is oxidized (d) is hydrolysed

(a) electron donation (c) reduction

(b) oxidation (d) hydrolysis

44) In the electrolysis the process of oxidation occurs at (a) anode (b) cathode (c) both cathode and anode (d) in electrolytic solution 45) In an oxidation process the oxidation number of the element (a) increases (b) decreases (c) does not change (d) None 46) Oxidation number of oxygen in OF2 is (a) + 1 (c) + 2

(b) - 1 (d) – 2

47) A substance which in molten state or in solution form allows electric current to pass is (a) electrolyte (b) insulator (c) conduction (d) none of these 48) An apparatus in which chemical energy in converted to electrical energy is called (a) electrolytic cell (b) galvanic cell (c) fuel cell (d) down cell 49) Sodium metal is obtained by the electrolysis of fused NaCl in a cell is called (a) Nelson’s cell (b) Down’s cell (c) Daniell cell (d) Voltaic cell 50)

The change in heat energy of a chemical reaction at constant temperature and pressure is (a)enthalpy change (b) bond energy (c)heat of sublimation (d) internal energy change

51)

Calorie is equivalent to (a)0.4184 J (c)4.184 J

52) The unit of enthalpy change is (a)calorie (c)volt

(b) 41.84 J (d) 418.4 J

(b) joule (d) coulomb

53) The freezing mixture used in ice cream machine consists of ice and (a)NaCl (b) CaCl2 (c)KNO3 (d) both a & c 54) The term cryoscopy is used (a)depression of freezing point (c)lowering of vapour pressure

(b) elevation in boiling point (d) osmotic pressure

55) The term ebullioscopy is used (a)depression of freezing point (c)lower of vapour pressure

(b) elevation in boiling point (d) none of above

56) Which one of following is not a conjugate solution (a)ether + water (b) phenol + water (c)nicotine + water (d) ethanol + water 57) Solubility of following decrease with increase in temp (a)Ce2(SO4)3 (b) CaCl2 . 6H2O (c)Pb(NO3)2 (d) K2Cr2O7

58) The unit of Debye is _______ a) 3.336x10-30C.m b) 3.336x10-28C.cm

c) 3.336x10-27C.mm d) All of these

59) Convert 160 mm Hg into Kpa ________ a) 22Kpa b) 23.12Kpa

c) 24.12Kpa

60) The mass of one mole of electron is _________ a) 08mg b)0.55mg c) 5.48 X 10-7 Kg

d) 21.33Kpa

d) All of b, c

61) The order of the rate of diffusion of gases NH3, SO2, Cl2 and CO2 is ______ a) NH3 > SO2 > Cl2 > CO2 b) NH3 > CO2 > SO2 > Cl2 c) CO2 > NH3 > SO2 > Cl2 d) SO2 > NH3 > CO2 > Cl2 62) The number of bonds in N2 molecule are __________ a) 1σ 2π b) 1σ 1π c) 2σ 1π

d) 3σ

63) Which of the following molecule has zero dipole moment ________ a) NH3 b) H2O c) ChCl3 d) BF3 64) Which of the following has unpaired electrons in antibonding molecular orbital____ a) N2-2 b) O2+2 c) B2 d) F2 65) d-orbitals have number of degenerate orbitals _________ a) 6 b) 5 c) 4 66) SnCl4 shows geometry _______ a) Trigonal b) Angular

d) 3

c) Pyramidal

d) Tetrahedral

67) Correct geometry for Trans 1,2 - dichloroethene is _________

a)

b)

c)

d)

68) Unite of b in Van Der Waal’s equation is _______ a) dm3.mole b) dm3.mole-2 c)dm3.mole-1.atm

d) dm3.mole-1

69) Color of Br4 gas is ______ a) Reddish blue b) Dark blue

d) Brown

c) Reddish Brown

70) The rate of evaporation increases when ____________ a) Increase in T b) Increase in Surface Area c) Weak forces

d) All a,b & c

71) In winter the viscosity of blood __________ a) Decreases b) Increases

d) Double decrease

72) One dyne is equal to _________ a) 10-5 N b) 10-3 N

c) Constant

c) 10-6 N

d) 10-7 N

73) Equal masses of methane and oxygen are mixed in an empty container at 25 oC, the fraction of total pressure exerted by O2 is________ a) 8/9 b) 1/3 c) 1/9 d) 3/1 74) The percentage of Nitrogen in Urea (NH2)2CO is ___________ a) 46.7% b) 34.4% c) 40%

d) 45%

75) The molecules of which of the following gases have the greater average molecular speed at 300K? a) Argon b) Neon c) Flourine d) Chlorine 76) In NaCl, each Na+1 ion is surrounded by __________ a) 4 Cl-1 ions b) 5 Cl-1 ions c) 6 Cl-1 ions

d) 2 Cl-1 ions

77) Salts which absorbs moisture from the atmosphere are called _________ a) Hydroscopic salt b) Celtic salt c) Kosher salt d) Hygroscopic salt 78) Probability of finding the electrons in π bond is ___________ a) Minimum at nodal plane b) Maximum at nodal plane c) Maximum in the region above and below nodal plane d) Both a&c 79) PH3 is an example of _______ a) AB3 type

b) Ab3E type

c) AB2E2 type

d) AB2E type

80) At normal boiling point of substance, the vapour pressure of the substance __________ a) Equal to 760cm of Hg b) Different for different substances c) Equal to 760torr d) Does not have a definite value 81) If the maximum area of orbitals is shared during overlapping, it means _______ a) Maximum energy loss b) Minimum energy loss c) Energy stays constant d) Maximum gain of energy 82) If the temperature and pressure of 2dm3 of CO2 are doubled, then volume of CO2 would become a) 8 dm3 b) 6 dm3 c) 4 dm3 d) 2 dm3 83) If 10g of a gas at 1atm pressure is cooled from 2730C to 0 0C at constant volume, it’s pressure would become ______ a) 2atm b) 1atm c) ½ atm d) 273atm 84) The density of methane at 2atm pressure and at 27 0C is ______ a) 26 g dm-3 b) 0.26 g dm-3 c) 1.30 g dm-3 d) 0.13g dm-3 85) The spreading of fragrance of perfume in air is due to ________ a) Effusion b) Diffusion c) Osmosis d) Density 86) What is the mass of Sodium present in 30g of Sodium Chloride________ a) 23g b) 11.79g c) 44.85g d) 35.5g

IMPORTANT SHORT QUESTIONS FROM ALL CHAPTERS Why σ2Px is not equal to π2Py, π2Pz according to molecular orbitals energy level although they all are degenerate orbitals? A puff of smoke weighs 0.1 gram. How many atoms are present (Assume smoke is pure Carbon)? Why e/m value of cathode rays is same for all gases? Justify that the distance gap between different orbitals increases from lower to higher orbitals? A photon of wave number 102.70 X 105m-1 jumps from higher orbital to n = 1. Find the number of orbit from where the electron falls? Find the percentage composition of Nitrogen in NH2CONH2? Why SiF4 does not show Dipole moment? Why lone pair acquires more space as compared to bond pair? The bond length of HBr is 1.4 x 10-10m and it’s observed dipole moment is 0.79D. Find the percentage ionic character of the bond? (Unite positive charge 1.6022x10-19 C) Where is the maximum probability of finding the electrons in σ and π bond? Find the value of Ideal gas constant when units are cm3 torr mol-1 K-1? Why water vapors do not behave ideally at 273K? Why water boils at 120 0C in pressure cooker? Draw a graph showing the effect of temperature on vapor pressure of Ethanol, Water, Diethyl ether and Ethylene glycol? Give any three uses of liquid crystals? What type of intermolecular forces will dominate in the following liquids, NH3, C8H18 and CH3COCH3 ? What is Anisotropy and Allotropy? How to get Sodium Chloride from Saline solution? KCl (solid) and KCl (Liquid) which one of them can conduct electricity and which can not, give your reason? A very well known gas is enclosed in container having volume of 500 cm3 at STP, it’s mass comes out to be 0.72g. What is the molar mass of this gas? How many covalent bonds are present in 9g of water? Differentiate between limiting and non limiting reactant? How many molecules of water are there in 12 g of ice? Define the theoretical and actual yield? What is conversion factor? What is the relationship between mass and volume of gas at STP? Why actual yield is lesser than theoretical yield? How mass of electon can be calculated from e/m ratio and charge? How does Mosley’s Law help in the production of X-rays? Which quantum number is also called sub shell quantum number? What is the difference between Orbit and Orbital? Why is 4s orbital lower in energy than 3d orbital? What is (n+l) rule? Differentiate between Frequency and wavelength? State some defects of Bohr’s model? Differentiate between Molecular Solids and metallic solids? What is Bond Order? Differentiate between Paramagnetism and Diamagnetism? What is Hybridization? Give some drawbacks of Valence Bond Theory For What purpose Calorimeter is used?

State the Hess’s law of constant heat of summation? What is Born-Haber cycle? What is it advantage? Explain the term Enthalpy? Prove that change in Enthalpy is equal to heat of reaction? What is meant by standard enthalpy of atomization and also give example? How many covalent bonds are present in 34 grams of ammonia(NH3) ? [At.masses N=14,H=1] Using Bohr’s equation calculate the distance travelled by an electron of a Hydrogen atom when it jumps from 1st to 2nd orbit. Write three properties of canal rays. Describe the shape of following molecules by using VSEPR concept; a. PH3 b. H2S Explain sigma bond and Pi bond giving one example in each case. What is plasma? Give its four properties. What is vapour pressure of a liquid? Discuss the effect of temperature and intermolecular forces on the vapour pressure. Give two definitions of Lattice Energy with an example in each case. Calculate pH of a Buffer solution containing 0.1 M acetic acid (CH3COOH) and 1.0 M sodium acetate (CH3COONa). The pKa for acetic acid is 4.76. Use the concept of Hydrolysis to explain why aqueous solutions of some salts are acidic, basic or neutral, Define the following: a. Average rate of reaction b. Instantaneous rate of reaction c. Order of reaction The reaction given below is first order in H2 and half order in Br2 : H2ig) + Br2(g) -> 2HBr(g) Write rate equation (rate law) of the reaction and deduce overall order of reaction. Calculate the mass percent of a solution containing 10 grams of sugar and 100 grams of water. Using Raoult’s law prove that the Relative Lowering of vapour pressure is equal to the mole fraction of the non-volatile, non-electrolyte solute. What is lionization energy? Why is the 1st I.E < 2nd I.E and so on? Why does the I.E increase along the period? Why do the boiling points of noble gases increase down the group? Freshly cut surface of the metal is shiny. Why? What is order of reaction? Give an example of zero order reaction? Define Molar heat of Vaporization and Molar heat of Sublimation Explain why heat of sublimation of a substance is greater than heat of vaporization. State and explain Hess’s law using a general reaction. Balance the following Redox equation by using oxidation number method: NaCI02 + Cl2NaO + CI02