laboursonline – MCQs, Mock Tests | Chemistry Chemistry MCQ Question

Hypochlorous acid is used for disinfecting the water it reacts with the dissolved ammonia producing

1. NH2Cl
2. NHCI2
3. NCI2
4. all of the above

✅ Correct Answer: 4

Acid present in acid rain may be

1. H2SO4
2. HNO3
3. both a and b
4. none

✅ Correct Answer: 3

The yellow colour in photochemical smog is due to presence of

1. dinitrogen oxide
2. nitrogen dioxide
3. chlorine gas
4. chlorine dioxide

✅ Correct Answer: 2

Which of the following is not a condition for the formation of smog?

1. sufficient NO
2. sunlight
3. less movement of air
4. winds

✅ Correct Answer: 4

Incineration of muncipal waste is carried out in the temperature range of

1. 250 to 500?C
2. 500 to 900?C
3. 950 to 1300?C
4. 900 to 1000?C

✅ Correct Answer: 4

In which of the following layer of atmosphere there is more thickness of ozone layer?

1. troposphere
2. stratosphere
3. mesosphere
4. photosphere

✅ Correct Answer: 2

Which of the following is not primary pollutant

1. SO3
2. CO
3. NO
4. H2SO4

✅ Correct Answer: 4

Which of the following air pollutants is more dangerous for ozone layer?

1. CFC
2. CO2
3. CO
4. Oxides of nitrogen

✅ Correct Answer: 1

Which of the following gases is the main cause of acid rain?

1. CO
2. NO2
3. both a & b
4. none of the above

✅ Correct Answer: 2

Which statement is wrong?

1. the amount of ozone layer is greater in the region close to the equator
2. ozone acts as filter for UV radiations
3. in the equatorial region it acts as pollutant
4. CFCs play effective role in removing O3 in the stratosphere

✅ Correct Answer: 1

Which of the following factors help to measure quallity of water?

1. DO
2. BOD
3. COD
4. all of the above

✅ Correct Answer: 4

In the purification of portable water the coagulant used is

1. alum
2. nickel sulphate
3. copper sulphate
4. barium sulphate

✅ Correct Answer: 1

Newspaper can be recycled again and again how many times?

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

✅ Correct Answer: 4

The main pollutant of leather tanneries in the waste water is

1. chromium III
2. chromium IV
3. chromium V
4. chromium VI

✅ Correct Answer: 2

A single chlorine free radical can destroy how many ozone molecules?

1. 10
2. 100
3. 10000
4. 100000

✅ Correct Answer: 4

Which substance can be used for disinfecting water?

1. KMnO4
2. Alums
3. Ozone
4. All

✅ Correct Answer: 1

Chlorination of water may be harmful if the water contains

1. Ammonia
2. Dissolved oxygen
3. Carbon dixide
4. All

✅ Correct Answer: 1

Which one of the following makes the bulk of hydrospheres content?

1. oceans
2. glaciers & icecaps
3. fresh water lakes and ponds
4. All have equal distribution

✅ Correct Answer: 1

Which of the following is used as water disinfectant to avoid the formation of toxic compounds

1. Cl2
2. O3
3. ClO2
4. both b & c

✅ Correct Answer: 4

The percentage of suspended solid waste in raw water is removed by coagulation is

1. 60
2. 70
3. 80
4. 90

✅ Correct Answer: 3

Ozone hole is substantial depletion of ozone in every year during

1. Aug - Nov
2. Sep - Nov
3. Nov - Dec
4. Dec - Jan

✅ Correct Answer: 2

The main product of bacterial action is

1. Nox
2. NO2
3. N2O3
4. NO

✅ Correct Answer: 4

Pollutants have adverse effect over

1. Biosphere
2. Ecosystem
3. Both a & b
4. Hydrosphere

✅ Correct Answer: 2

Diameter of an atom is in the order of

1. 0.2m
2. 0.2mm
3. 0.2nm
4. 0.2pm

✅ Correct Answer: 3

Which of the following are isoelectronic species?

1. H+ H H-
2. Li+ Na+ K+
3. C1- Br- I
4. F- Ne Na+

✅ Correct Answer: 4

Mass spectrometer is used to determine Mass number of isotopes and

1. Atomic number
2. Relative abundance
3. Electronic configuration
4. All of the above

✅ Correct Answer: 2

Molecular ions are formed by passing

1. High energy electron beam
2. ? - particle
3. X-rays
4. All of the above

✅ Correct Answer: 4

The number of peaks obtained in mass spectrometry shows

1. Relative abundance
2. Average mass of element
3. Number of isotopes
4. Relative isotopic mass

✅ Correct Answer: 3

Empirical formula of chloroform is

1. CH2 C12
2. CH3C1
3. CC14
4. CHC13

✅ Correct Answer: 4

Which one is true about isotope?

1. Same number of neutrons
2. Same mass number
3. Same physical properties
4. Same chemical properties

✅ Correct Answer: 4

Molecular mass of water (18g) means

1. 1-mole molecules of water
2. 1-gram molecule of water
3. 3-gram atoms
4. all

✅ Correct Answer: 4

Which of the following ion formation is always exothermic?

1. Uni-negative
2. Uni-positive
3. Di-negative
4. Di-positive

✅ Correct Answer: 1

Which of the following statements about isotopes is correct?

1. Isotopes with odd atomic number are abundant
2. Isotopes with odd atomic number and even mass number are abundant
3. Isotopes with even atomic number and even mass number are abundant
4. Isotopes with even atomic number and odd mass no are abundant

✅ Correct Answer: 3

The sample of isotopes of an element which needs not to be vaporized in the vaporization chamer

1. Gas
2. Liquid
3. Volatile solid
4. All

✅ Correct Answer: 1

One mole of CO2 contains.

1. 6.022 x 1023 atoms of oxygen
2. 22-gram electrons
3. 6.022 x 1023 atms of carbon
4. both b & c

✅ Correct Answer: 4

Avogadros number may represent

1. volume of particles
2. number of particles
3. mass of particles
4. All of the above

✅ Correct Answer: 4

The number of isotopes of elements with even mass number and even atomic number are.

1. 280
2. 300
3. 154
4. 54

✅ Correct Answer: 3

Size of molecule depends upon

1. Atomicity
2. Shape of molecule
3. Both a and b
4. Difficult to predict

✅ Correct Answer: 3

Which of the following terms is not used for ionic compound?

1. formula unit
2. empirical formula
3. molecular formula
4. formula mass

✅ Correct Answer: 3

0.36 moles of each aluminium and oxygen react with each other to produce aluminium oxide. The amount of product formed is

1. 0.18 mole
2. 0.27 mole
3. 0.24 mole
4. 0.09 mole

✅ Correct Answer: 1

Which of the following terms is used for the mass of chlorine 35.5?

1. relative atomic mass
2. mass number
3. atomic weight
4. relative isotopic mass

✅ Correct Answer: 1

Which one of the following has the maximum number of isotopes?

1. oxygen
2. carbon
3. tin
4. chlorine

✅ Correct Answer: 3

Which one of the following is not the mono isotopic element?

1. arsenic
2. uranium
3. iodine
4. nickel

✅ Correct Answer: 2

The volume occupied by 2.8 g of N2 at STP

1. 2.24 dm3
2. 22.4 dm3
3. 1.12 dm3
4. 112 dm3

✅ Correct Answer: 1

The mass of decimole of electrons (NA) is

1. 1.008 mg
2. 0.184 mg
3. 0.054 mg
4. 5.4 mg

✅ Correct Answer: 3

The number of moles of CO2 which contains 16 g of oxygen is

1. 0.25
2. 0.5
3. 0.75
4. 1

✅ Correct Answer: 2

Which of the following statements is wrong about isotopes?

1. they possess different mass number
2. they possess different physical properties
3. they possess same chemical properties
4. they possess different position in the periodic table

✅ Correct Answer: 4

How many isotopes have odd atomic number?

1. 154
2. 280
3. 86
4. 300

✅ Correct Answer: 3

Qualitative analysis is carried out for

1. identification of elements
2. estimation of amounts of elements
3. molar ration of elements
4. molar volume of elements

✅ Correct Answer: 1

Percentage of calcium in calcium carbonate is

1. 80%
2. 30%
3. 40%
4. 20%

✅ Correct Answer: 3

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