Why mcqs of class 11 Chemistry lesson 7 Equilibrium is important ?
- these mcqs are important because these questions cover a wide topic of the chapter
- mcqs are easy to understand
- mcqs break the big topic in some small topic so they are easy to learn
- they give a short revision at the time of class 11 Chemistry exam
How to get pdf of class 11 Chemistry lesson 7 Equilibrium mcqs
Increasing role of mcqs in board exam
(1) Chemistry does not play a major role in:
Explaining superconductivity
Design and synthesis new materials having specific magnetic, electric and optical properties.
Explaining ozone depletion.
Large scale production of a variety of fertilizers.
Answer - A
Explanation - Chemistry does not deal with explaining superconductivity.
*In superconducting materials the characteristics of superconductivity appear when the temperature is lowered below a critical temperature.
*The onset of superconductivity is accompanied by abrupt changes in physical properties which are more related to phase transitions of the material.
These aspects of studies in properties of materials are better related to studies in the fields of Physics, even though principles involved in Chemistry & Physics go hand to hand.
(2) Matter can be classified at the macroscopic or bulk level as:
Elements and molecules
Atoms and molecules
Solids and liquids
mixtures or pure substances
Answer - D
Explanation - At the macroscopic level, the matter is classified as a mixture or pure substances. A mixture contains two or more components (in any ratio ) present in it, for example -- sugar solutions in water, tea, air, alloys like brass, bronze, etc. Pure substances (viz. copper, silver, gold, water, glucose, etc.) have a fixed composition. The constituents of pure substances can not be separated by simple physical methods.
(3) In a homogeneous mixture, the components are:
do not mix with each other and its composition is not uniform throughout.
completely mix with each other and its composition is not uniform throughout.
do not mix with each other and its composition is uniform throughout.
completely mixed with each other and its composition is uniform throughout.
Answer - D
Explanation - In a homogeneous mixture,
the components are mixed together completely.
has a uniform composition throughout.
(4) Which of the following statements about pure substances is correct?
Pure substances are elements only.
Pure substances do not have fixed composition.
Pure substances have fixed composition.
Pure substances are compounds only
Answer - C
Explanation - Pure substances have a fixed composition. These may be both (i.e. either elements or compounds). The law of constant composition holds good for such substances.
(5) Particles of compounds are:
atoms
molecules of two or more atoms of different elements
homogeneous mixtures
heterogeneous mixtures
Answer - B
Explanation - Compounds are made when atoms of two or more different elements combine together in a fixed ratio to form molecules (viz. water, ammonia, carbon dioxide, glucose, etc. ). Thus the particles of the compound consist of molecules.
(6) Fill up the blanks with a suitable word in the statement, " Physical properties are those properties which are measured or observed ________ changing the identity or the composition of the substance ."
by
with
without
After
Answer - C
Explanation - A substance is identified by its composition, hence for measuring physical properties of a substance its identity must be retained, (or should not be changed) Hence, the given statement, " Physical properties are those properties which are measured or observed without changing the identity or composition of the substance." is correct.
(7) SI units for Base Physical Quantities of length, mass, and current are:
meter, gram, ampere
meter, kilogram, candela
decimetre, kilogram, ampere
meter, kilogram, ampere
Answer - D
Explanation - The International System of Units ( abbreviated as SI ) is a modern form of the metric system and is the most widely used form of measurements.
It comprises a coherent system of measurement built of seven base units.
The base units for length, mass, and current in this system of measurements are, " meter, kilogram, ampere" symbolized respectively as m, kg, A.
(8) SI unit of density is:
kg-1m3
kg m-3
kg m-2
kg m3
Answer - B
Explanation - Since density = mass / volume and SI unit of mass is kg and that of the volume is m3
∴ using these SI units the unit of density is derived through dimensional analysis:
density = mass / volume
= kg / m3
or, = kg m-3
(9) The Kelvin scale is related to celsius scale as:
K = °C + 100
K = °C + 32
K = °C + 212
K = °C + 273.15
Answer - D
Explanation - The relation between the Kelvin scale & Celsius scale of temperatures is -
K = °C + 273.15
Such a relationship is based upon the experimental findings and subsequent conclusion of Charle's law.
The Kelvin scale is also termed as an "absolute scale of temperature."
It is interesting to note that temperature below 0oC ( ie. negative values ) is possible in the Celcius scale but in Kelvin scale, the negative temperature is not possible.
(10) In scientific notation for numbers, any number can be represented in the form, N × 10n where,
n is an exponent having positive or negative values and N can vary from 0 to 1.
n is an exponent having positive or negative values. N represents a number that can vary from 1 to 10, but not 10 itself.
n is an exponent having positive values only and N can vary from 1 to 10.
n is an exponent having positive or negative values and N can vary from 10 to 100.
Answer - B
Explanation - Scientific notation is conveniently used to represent extremely large or even very small numerical values. It is an exponential notation in which any number can be represented in the form, N × 10n, where n is an exponent having positive or negative values and N can vary between 1 and 10, but not 10 itself.
(11) Precision and Accuracy refer to _______ of various measurements for the same quantity repeatedly and agreement of particular value to the _________ of the result, respectively.
closeness , other values
closeness, the true value
minimum , true value
maximum , true value
Answer - B
Explanation - Precision means the closeness of all the data values measured while accuracy means the closeness of a particular value with the real value.
For example,
when the reported values are 2.01, and 1.99 gas the result and its true value is 2.00 g.
These values are both precise and accurate.
(12) Significant figures are:
first three digits after the decimal point
digits before the decimal point
digits after the decimal point
meaningful digits which are known with certainty
Answer - D
Explanation - Significant digits are certain digits that have significance or meaning to certain digits in a number. Such digits help scientists to use them with more precise information about measurement and other numeric data. These digits also help them in rounding off a very large or very small number
(13) According to Gay Lussac’s Law of Gaseous Volumes, " when gases combine or are produced in a chemical reaction they do so in a ______ ratio by volumes provided all gases are at the same temperature and pressure."
simple
equal
inverse
Uncertain
Answer - A
Explanation - Gay lussac’s law states that when gases combine or are produced in a chemical reaction they do so in a simple ratio by volume provided all gases are at the same temperature and pressure.
Mathematically, the law is expressed as,
[V/n] = k
where V represents the volume of the gas, n denotes the number of moles of the gas & k is the proportionality constant.
Thus, the volume ratio must be related to the relative number of molecules.
This relationship was crucial in establishing the formula of simple molecules at a time when a distinction between atoms and molecules was not clearly understood.
(14) According to Avogadro Law, equal volumes of all gases at the same temperature and pressure should contain _______ number of molecules.
different
unequal
similar
Equal
Answer - D
Explanation - Avogadro's law states that " equal volumes of all gases at the same temperature and pressure contain an equal number of molecules."
(15) Molecular mass of a compound is the ________ of atomic masses of elements present in a molecule.
average
sum
maximum
Lowest
Answer - B
Explanation - Molecular mass is the sum of atomic masses of the elements present in a molecule.
For example ; Molecular mass of CO2 = Σ atomic mass of one carbon atom & atomic mass of two oxygen atoms
= [ 12 + 2(16) ]u
= 44u.