laboursonline – MCQs, Mock Tests | Chemistry Chemistry MCQ Question

Combustion analysis is performed to determine

1. Empirical formula
2. Molecular mass
3. Molecular formula
4. Formula mass

✅ Correct Answer: 1

Mostly elements have fractional atomic masses because of

1. mass of an atom itself is in fraction
2. atomic masses are average masses of isobars
3. atmoic masses are average masses of isotopes proportional to their relative abundance
4. atmoic masses are average masses of isotopes

✅ Correct Answer: 3

Isotopes differ in

1. properties which depend upon mass
2. arrangement of electrons in orbitals
3. chemical properties
4. all of the above

✅ Correct Answer: 1

Which of the following is not a macromolecule?

1. sand
2. haemoglobin
3. diamond
4. maltose

✅ Correct Answer: 4

Which of the following methods is used to estimate hydrogen in an organic compound?

1. Combustion method
2. Dumas method
3. Kjeldahls method
4. All of the above methods are for different purposes

✅ Correct Answer: 1

Isotopes of the same elements has

1. different number of protons
2. same number of neutrons
3. different number of neutrons
4. same mass number (nucleon number)

✅ Correct Answer: 3

The nucleus of an atom of every element will always contain

1. neutrons
2. protons and electrons
3. protons
4. protons and neutrons

✅ Correct Answer: 3

When cationic molecular ions are allowed to pass through strong magnetic field in mass spectrometer which of the following ions is fallen

1. lighter
2. intermediate
3. heavier
4. are collected at same time

✅ Correct Answer: 1

When 0.5 mole of phosphoric acid is dissolved in aqueous solution how many moles of -ve and +ve ions are collected altogether?

1. 0.5
2. 1
3. 1.5
4. 2

✅ Correct Answer: 4

For which of the following compounds the term empirical formula cannot be applied?

1. NaCl
2. H2O
3. CCI4
4. It can be applied to all mentioned above

✅ Correct Answer: 4

Dempsters mass spectrometer has number of zones / parts

1. 5
2. 4
3. 3
4. 2

✅ Correct Answer: 1

The properties of an element mosly corresponds to that isotope which has greater

1. Mass number
2. Atomic mass
3. Relative abundance
4. all of the above

✅ Correct Answer: 3

1 a.m.u =

1. 1.6 x 10-27 kg
2. 1.6 x 10-24 kg
3. 1.6 x 10-26 kg
4. 1.6 x 10-28 kg

✅ Correct Answer: 1

Which of the following has strongest intermolecular forces of attraction?

1. Hydrogen (H2)
2. Chlorine (Cl2)
3. lodine (I2)
4. Methane (CH4)

✅ Correct Answer: 3

Which has strongest bonding in the solid state?

1. Hydrogen Chloride (HCI)
2. Chlorine (Cl2)
3. Xenon(Xe)
4. Sodium Chloride (NaCI)

✅ Correct Answer: 4

When substance moves from a solid to a liquid state all of the following changes occur except

1. Molecules become more disordered
2. K.E of the molecules decreases
3. Intermolecular forces become weaker
4. Molecule become further separated

✅ Correct Answer: 2

When the atoms of third layer are arranged in such a way that they directly lie above the atoms of first layer then this arrangement is called

1. ABAB (hexagonal)
2. ABCABC (Cubic)
3. Orthor hombic
4. Rhombohedral

✅ Correct Answer: 1

In order to mention the boiling point of water at 110?C the external pressure should be

1. Between 760 torr and 1200 torr
2. Between 200 torr and 760 torr
3. 765 torr
4. any value of pressure

✅ Correct Answer: 1

Which one is false for evaporation?

1. Surface phenomenon
2. Continuous
3. Exothermic
4. Cause cooling

✅ Correct Answer: 3

Vapour pressure of water at 100?C is

1. 55 mm Hg
2. 760 mm Hg
3. 355 mm Hg
4. 1489 mm Hg

✅ Correct Answer: 2

Which one of the following does not show hydrogen bonding ?

1. Water
2. Ethyl alcohol
3. Phenol
4. Diethyl ether

✅ Correct Answer: 4

Liquid crystal is discovered by

1. William Crooks
2. Fredrack Reinitzer
3. J.J Thomson
4. Bravis

✅ Correct Answer: 2

Which one is a conductor but is not malleable?

1. Iron
2. Graphite
3. Silver
4. Platinum

✅ Correct Answer: 2

Hydrogen bonding is involved in

1. Solubility
2. Cleansing action of detergents
3. Biological molecules
4. All

✅ Correct Answer: 4

Actually the vapour pressure on the surface of liquid in the flask is equal to

1. ? h
2. Pa - ?h
3. Pa + ?h
4. Pt = Pa - ?h

✅ Correct Answer: 3

Forces of attraction which may be present between all kinds of atoms and molecules are

1. intramolecular
2. intermolecular
3. van der Waal
4. Dipole-induced dipole

✅ Correct Answer: 3

The density of water may be

1. Equal to that of ice
2. Greater than that of ice
3. Less than that of ice
4. All are possible

✅ Correct Answer: 2

The quantity of heat required to convert one mole of liquid into its vapours at its boiling point is called molar heat of

1. vaporization
2. evaporation
3. crystallization
4. sublimation

✅ Correct Answer: 1

Steam causes more sever burn than the boiling water because it possesses.

1. Latent heat of fusion
2. Latent heat of vaporization
3. Latent heat of sublimation
4. All of the above

✅ Correct Answer: 2

Water has maximum density at

1. 0?C
2. 2?C
3. 4?C
4. 100?C

✅ Correct Answer: 3

The conversion of vapours back into their liquid state is called

1. crystallization
2. evaporization
3. vaporization
4. condensation

✅ Correct Answer: 4

Formation of vapours from the surface of a liquid is called

1. vapourization
2. evaporation
3. condensation
4. cracking

✅ Correct Answer: 2

When water freezes at 0?C its density decreases due to

1. Change of bond angles
2. Cubic structure of ice
3. Empty space present in the structure of ice
4. Change of bond length

✅ Correct Answer: 3

The ttractive forces between the partial positive end of one molecule and partial negative end of other molecule are called

1. Dipole-dipole forces
2. Ion dipole-dipole forces
3. London dispersion forces
4. Debye forces

✅ Correct Answer: 1

The boiling point increases down the zero group element due to

1. Ion dipole forces
2. London forces
3. Hydrogen bonding
4. Dipole dipole forces

✅ Correct Answer: 2

Vapour pressure is not affected by

1. Surface area
2. temperature
3. intermolecular forces
4. atmospheric pressure

✅ Correct Answer: 1

Rising of a wetting liquid in a capillary tube is due to

1. Surface tension
2. Cohesive forces
3. Adhesive forces
4. viscosity

✅ Correct Answer: 3

Table salt crystallizes with a

1. Face centered cubic lattice
2. body centered cubic lattice
3. simple cubic lattice
4. othorhombic lattice

✅ Correct Answer: 2

The number of formula units in 29.25g of common salt

1. 6.022 x 1023
2. 3.01 x 1023
3. 2 x NA
4. 4 x 6.022 x 1023

✅ Correct Answer: 2

During which process empty spaces between particles become minimum?

1. ionization
2. condensation
3. fusion
4. evaporation

✅ Correct Answer: 2

Liquid gets the shape of the container when it is poured into it. Which one of the following reasons justifies it?

1. Liquid do not have definite shape
2. Liquid do not have definite volume
3. Lieuid is highly compressible
4. Liquid molecules can slide over each other

✅ Correct Answer: 4

Which one of the following has highest volatility

1. Diethyl ether
2. Ethyl alcohol
3. Water
4. Ethylene glycol

✅ Correct Answer: 1

Molar heat of vaporization of water is

1. 40.7 KJ/mole
2. 40.7 J/mole
3. 40.7 cal/mole
4. 40.7 Kcal/mole

✅ Correct Answer: 1

If we provide very high amount of heat to a liquid its boiling point will

1. increase
2. remains constant
3. decrease
4. there will be no boiling

✅ Correct Answer: 2

Crystallites are present in

1. crystalline solids
2. amorphous solids
3. liquid crystals
4. all of the above

✅ Correct Answer: 2

A solid may be made up of

1. Atoms
2. Ions
3. Molecules
4. a b and c

✅ Correct Answer: 4

A malleable solid is one which can be

1. Converted into wires
2. Converted into thin sheets
3. Melted easily
4. All of the above

✅ Correct Answer: 2

Amorphous substances posses

1. No definite geometry
2. No definite heat of fusion
3. No sharp melting points
4. All of the above

✅ Correct Answer: 3

Crystalline solids can be identified easily from their

1. Sharp melting point
2. Definite geometry
3. Transition temperature
4. Colour

✅ Correct Answer: 1

Boiling points of hydrocarbons increase with the increase in number of carbon atoms. It is mainly due to

1. More strength of H-bonding
2. More strength of London forces
3. Less polarizability
4. All of the above

✅ Correct Answer: 2

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