Some Basic Concepts of Chemistry
Chapter 1
ASSERTION
AND REASON TYPE QUESTIONS (1 MARK) In the following questions, a statement of
Assertion (A) followed by a statement of Reason (R) is given.
Choose
the correct option out of the choices are given below.
(A)
Both A and R are true and R is the correct explanation of A.
(B)
Both A and R are true but R is not the correct explanation of A.
C)
A is true but R is false.
(D)
Both A and R are false.
1.
Assertion : Equal
moles of different substances contain same number of constituent particles.
Reason
: Equal weights of
different substances contain the same number of constituent particles.
2.Assertion
: One atomic mass
unit is defined as one-twelfth of the mass of one carbon-12 atom.
Reason
: Carbon-12
isotope is the most abundant isotope of carbon and has been chosen as the
standard.
3.Assertion
(A) : Significant
figures for 0.200 is 3 where as for 200 it is 1.
Reason
(R) : Zero at the
end or right of a number are significant provided they are not on the right
side of the decimal point.
4.The
number of atoms present in one mole of an element is equal to Avogadro number.
Which of the following element contains the greatest number of atoms?
(a)
4g He (b) 46g Na (c)
0.40g Ca (d) 12g He
5.The
significant figures in 0.00051 are ————–. (a) 5 (b) 3 (c) 2 (d) 26
6.How
many moles of electrons weight one kilogram?
(a)
6.023 × 10 23 (b) 1/9.1 × 10 31 (c)
6023×10 54 (d)
9.1 × 108
7.Calculate the number of atoms in each of the following
(i) 52 moles of Ar (ii) 52 u of He
8.What
is the mass percent of hydrogen in in water?
(a)
0.034% (b) 11.1% (c)
3.4% (d) 28.7%
9.Which
of the following contain highest number of atoms?
(a)
1.0 g of water (b) 1.0 g
of silver (c) 1.0 g of
nitrogen (d) 1.0 g of
propane
10.The
number of water molecules is maximum in
(a)
18 gram of water (b) 18 moles
of water (c) 18 molecules of
water (d) 1.8 gram of water
11.What
will be the molarity of a solution which contains 5.85g of NaCl per 500
ml?
(a)
4 mol/L (b)
0.2 mol/L (c) 20
mol/L (d) 2 mol/L
12.Give
an example of a molecule in which the ratio of the molecular formula is six
times the empirical formula.
13.(i)
State the law of constant composition (ii) Define molality.
14.Calculate
the amount of carbon dioxide that could be produced when
(i)
1 mole of carbon is burnt in air. (ii)
1 mole of carbon is burnt in 16 g of dioxygen.
15.What
is stoichiometry? What is the difference between precision and accuracy?
16.(a)
What do mean by molarity. Calculate the molarity of NaOH in the solution
prepared by dissolving its 4 g in enough water to form 250 mL of the solution.
17.Determine
the empirical & Molecular formulae for a compound with the following
elemental composition:40.00% C, 6.66% H, 53.34% O. (Given molecular mass = 180)
18.In
the reaction: 3C + 4D → 2A + 4B When 5 moles of A react with 6 moles of B then
(i) Which is the limiting reagent? (ii) Calculate the amount of C formed?
19.Which
aqueous solution has higher concentration: 1 molar or 1 molal solution of the
same solute? Give reason.
20.The
molecular mass of an organic compound is 78 and its percentage composition is
92.4 % C and 7.6 % H. Determine the molecular formula of the compound.
21.Dinitrogen
and dihydrogen react with each other to produce ammonia according to the
following chemical equation:
N2
(g) + H2 (g) →2NH3 (g)
(i)
Calculate the mass of ammonia produced if 2.00 x10 3 g dinitrogen reacts with
1.00 x103 g of dihydrogen.
(ii)
Will any of the two reactants remain unreacted?
(iii)
If yes, which one and what would be its mass?
22.Calcium
carbonate reacts with aqueous HCl to give CaCl2 and CO2 according to the
reaction given below: CaCO3 (s) + 2HCl (aq) → CaCl2(aq) +
CO2(g) + H2O
(l)
What mass of CaCl2 will be formed when 250 mL of 0.76 M HCl reacts
with 1000 g of CaCO3 ?
23
Name the limiting reagent. Calculate the number of moles of CaCl2
formed in the reaction
24.The
reactant which is entirely consumed in reaction is known as limiting reagent.
In the reaction 2A + 4B → 3C + 4D, when 5 moles of A react with 6 moles of B,
then-
(i)
which is the limiting reagent? (ii)
calculate the amount of C formed?
25.
Concentration of solutions: Molarity and Molality are the terms used to express
the concentration of the solution. The concentration of a solution is defined
as the measure of the quantity of one substance when it is mixed with another
substance. The concentration of a chemical solution is measured by both
molarity and molality. The major difference between the two is one of mass vs.
volume. The molality refers to the number of moles of the solute per unit mass
of the solvent, whereas the molarity refers to the number of moles of the
solute per unit volume of the solution. If the solution has a solvent and the
solute, a Mole Fraction gives a concentration as the ratio of moles of one
component to the total moles present in the solution. When the concentration is
expressed as the percent of one component in the solution by mass it is called
Mass Percentage.
Answer
the following questions:
a)
Give units of molality and molarity.
b)
Which concentration term is a dimensionless quantity? Give its
expression.
c)
Calculate the Molarity of 15 % H2SO4 solution by weight having density 1.1
g/mL.
Atomic
masses: H-1, S - 32, O-16
d)A
Solution contains 15gm of sugar in 60gm of water. Find out the mass % for sugar
in the solution
26.The
identity of a substance is defined not only by the types of atoms or ions it
contains, but by the quantity of each type of atom or ion. The experimental
approach required the introduction of a new unit for amount of substances, the
mole, which remains indispensable in modern chemical science. The mole is an
amount unit similar to familiar units like pair, dozen, gross, etc. It provides
a specific measure of the number of atoms or molecules in a bulk sample of
matter. A mole is defined as the amount of substance containing the same number
of discrete entities (atoms, molecules, ions, etc.) as the number of atoms in a
sample of pure 12C weighing exactly 12g. One Latin connotation for the word
“mole” is “large mass” or “bulk,” which is consistent with its use as the name
for this unit. The mole provides a link between an easily measured macroscopic
property, bulk mass, and an extremely important fundamental property, number of
atoms, molecules and so forth. The number of entities composing a mole has been
experimentally determined to be 6.02214179 × 10 23 .
(i)
How many moles of magnesium phosphate, Mg3(PO4)2
will contain 0.25 mole of oxygen atoms?
(a)
1.25 x 10 -2 (b) 2.5
x 10-2 (c) 0.02 (d) 3.125 x10-2
(ii)What
is the mass of one molecule of yellow phosphorus? (At. mass of phosphorus =30)
(a)1.993
x 10-22 mg (b)1.993 x 10-19
mg (c)
4.983 x 10-20 mg (d)
4.983 x 10-23 mg
(iii)
The number of moles of oxygen in 1L of air containing 21% oxygen by volume, in
standard conditions is
(a)
0.186 mol (b) 0.21 mol (c) 2.10 mol (d)
0.0093 mol
(iv)The
number of moles present in 6 gm of carbon is:
(a)
2 (b) 0.5 (c)
5 (d)
1
(v)
The mass of an atom of carbon is ————–.
(a)
1g (b) 1.99 x 10
-23 g (c)
1/12 g (d) 1.99 x 10 23 g
"Structure of Atom "
Chapter 2
ASSERTION
AND REASON TYPE QUESTIONS (1 MARK) In the following questions, a statement of
Assertion (A) followed by a statement of Reason (R) is given.
Choose
the correct option out of the choices are given below.
(A)
Both A and R are true and R is the correct explanation of A.
(B)
Both A and R are true but R is not the correct explanation of A.
(C)
A is true but R is false.
(D)
Both A and R are false.
1.
Assertion:
In Lyman series of H-spectra, the maximum wavelength of lines is 121.56nm.
Reason: Wavelength is maximum when
the transition is from the very next level.
2.Assertion:
According to Thomson model of atom, mass of the atom is concentrated in the
centre of the atom.
Reason:
According the Thomson model, positive charge is concentrated in the centre of
the atom.
3.Assertion
(A): It is impossible to determine the exact position and exact momentum of an
electron simultaneously.
Reason
(R): The path of an electron in an atom is clearly defined.
4.Assertion
(A) : Black body is an ideal body that emits and absorbs radiations of all
frequencies.
Reason
(R) : The frequency of radiation emitted by a body goes from a lower frequency
to higher frequency with an increase in temperature
5.Principal,
Azimuthal, and magnetic quantum numbers are respectively related to:
(a)
size , shape, and orientation (b)shape,
size and orientation
(c)
size, orientation and shape (d)
none of above
6.Which
of the following is responsible to rule out the existence of definite paths or
trajectories of electrons?
(a)
Pauli’s exclusion principle. (b) Heisenberg’s uncertainty
principle.
(c)
Hund’s rule of maximum multiplicity. (d) Aufbau principle
7.Which
of the following will not show deflection from the path on passing through an
electric field?
(a)
Proton (b) cathode rays (c)
electron (d)
neutron
8.The
magnetic quantum number specifies
(a)
Size of orbitals (b)
Shape of orbitals
(c)
Orientation of orbitals (d) Nuclear Stability
9.Consider
the isoelectronic series: K+ , S2- , Cland Ca2+, radii of the ions decrease
as
(a)
Ca2+ < K+ > Cl– , S2- (b)
Cl– > S2- > K+ > Ca2+
(c)
S2- > Cl– > K+ > Ca2+ (d)
K+ > Ca2+ > S2- > Cl-
10.Rutherford’s
Alpha particle scattering experiment eventually led to the conclusion
that
(a)
mass and energy are related (b)
electrons occupy space around the nucleus
(c)
neutrons are buried deep in the nucleus (d) the point of impact with matter can
be precisely determined
11.Which
of the following statement is not correct about the characteristics of cathode
rays?
(a)
They start from the cathode and move towards the anode.
(b)
They travel in straight line in the absence of an external electrical or
magnetic field.
(c)
Characteristics of cathode rays do not depend upon the material of electrodes
in cathode ray tube.
(d)
Characteristics of cathode rays depend upon the nature of gas present in the
cathode ray tube.
12.State
the following
(i)
Aufbau’s principle (ii)
Heisenberg uncertainty principle
13.Calculate
the wave number of line associated with the transition in Balmer series when
the electron moves to n = 4 orbit. (RH = 109677 cm–1 )
14.What
is Heisenberg’s uncertainty Principle? What is it’s significance?
15.Write
the electronic configuration of the Ni2+ (Z=28) and Cr (Z=24) .
16.Attempt
any 3 of the following
a)
State Pauli’s Exclusion Principle.
b)
Write the electronic configuration of Cu2+ ion.
c)
Calculate the total number of angular nodes and radial nodes present in the 3p
orbital.
d)
How many numbers of electrons having- n = 3 , m s = -½
17.The
order of screening effect of electrons of s, p, d and f orbitals of a given
shell of an atom on its outer shell electrons is: (i) s > p > d > f
(ii) f > d > p > s (iii) p < d < s > f (iv) f > p > s
> d
18.The
three dimensional space where probability of finding the electrons is maximum
is called
(a)
Orbit (b) Orbital (c) Octet (d) Nodes
19.Which
of the following is iso-electronic with neon -
(A)
O2– (B) F+ (C)
Mg (D) Na
20.The
value of l and m for the last electron in the Cl– ion are -
(A)
1 and 2 (B) 2 and +1 (C) 3 and –1 (D) 1 and –1
21.Which
of the following set of quantum numbers is not possible?
(a)
n = 3, l = 0, m = 0 ` (b) n = 3, l = 1,
m = -1
(c)
n = 2, l = 0, m = -1
(d) n = 2, l = 1, m = 0
22.The
ground state electronic configuration of Fe3+ ion is
(a)
[Ar] 3d3 4s2 (b)
[Ar] 3d6 4s2 (c)
[Ar] 3d5 (d) [Ar] 3d6
23.Which
of the following rule out the existence of definite path or trajectories of
electrons
(A)
Pauli’s exclusion principle (B) Heisenberg’s
uncertainty principle
(C)
Hund’s rule of maximum multiplicity (D)
Aufbau’s principle
What
were the reasons for it’s failure of Bohr’ model?
24.Find
the de Broglie wavelength for an electron moving at the speed of 2.19×10 6
ms−1
(Given:
Mass of an electron = 9.1×10-31 kg & h = 6.6 x 10 -34
Js)
25.(i)
State two postulates of Bohr’s model of hydrogen atom.
(ii)
Write a drawback of Bohr’s model of hydrogen atom.
26.a)
i) How many sub-shells are associated with n = 4 ?
ii)
How many electrons will be present in the sub-shells having ms value of -1/2
for n = 4 ?
b)
An ion with mass number 37 possesses one unit of negative charge. If the ion
contains 11 .1% more neutrons than the electrons, find the symbol of the ion.
27.(i)
Calculate wave number of yellow radiations having wavelength of 5800 A0 .
(ii)
What are the values of n and l for 4f orbital
28.Calculate
the wavelength and frequency of light wave whose period is 2.0 × 10-10
s.
29.(i)
The electron energy in hydrogen atom is given by En = (–2.18 x10-18)/n
2 J. Calculate the energy required to remove an electron completely from the n
= 2 orbit. What is the longest wavelength of light in cm that can be used to
cause this transition.
(ii)
Find the energy of the 3th Bohr’s orbit of He+ ion.
(iii)
Calculate the number of radial nodes for 2p orbital
30.(i)
How many electrons in an atom may have the following quantum numbers?
(a)
n = 4, ms = – ½ (b) n = 3, l = 0
(ii)
Show that the circumference of the Bohr orbit for the hydrogen atom is an
integral multiple of the de Broglie wavelength associated with the electron
revolving around the orbit.
(iii)
What is the maximum number of emission lines when the excited electron of a H
atom in n = 6 drops to the ground state?
31.Read
the given passage and answer the questions. Orbitals are regions or spaces
where there is a maximum probability of finding electrons. Qualitatively, these
orbitals can be distinguished by their size, shape, and orientation. An orbital
of small size means there is more chance of finding the electron near the
nucleus. Shape and orientation mean the direction in which the probability of
finding the electron is maximum. Atomic orbitals can be distinguished by
quantum numbers. Each orbital is designated by three quantum numbers n, l, and
ml (magnetic quantum number) which define energy, shape, and orientation but
these are not sufficient to explain spectra of multi-electrons atoms. Spin
quantumn number (ms ) determines the spin of electrons. Spin angular momentum
of the electron has two orientations relative to the chosen axis which are
distinguished by spin quantum numbers ms which can take values +1/2 and
–1/2
I.
How many orbitals are associated with n = 3?
II.
How many electrons are possible in an orbital? Why?
III.
What is the shape of ‘s’ and ‘p’ orbitals?
IV.
Name two d-orbitals that are on-axis.
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