Chemistry Archives - Pak Exam MCQs

Which one is not the characteristics of solids?

A. Definite Mass and Volume
B. Frequent Fludity
C. Rigidity
D. Definite Shape

Answer & Solution

Option: B
Explanation : Frequent Fluidity is not the characteristics of solids. Solid is one of the states of matter

Solid have Definite mass, volume, and shape because particles of matter are held together by strong intermolecular forces.

Solid have Short Intermolecular distance due to tight close packing.

Strong Intermolecular Forces because atoms and molecules are held close together.

Solids are incompressible and rigid in nature due to strong intermolecular forces acting on particles which keep them fixed on their positions.

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Which of the following metals is most reactive?

Chemistry 0

A. Sodium (Na)
B. Magnesium (Mg)
C. Coper (Cu)
D. Chlorine (Cl)

Answer & Solution

Option: A
Explanation :Metals can be ordered according to their reactivities.
1. Potassium (K) 2. Sodium (Na) 3. Calcium (Ca) 4. Lithium (Li) 5. Magnesium (Mg) 6. Aluminum (Al) 7. Zinc (Zn) 8. Iron (Fe) 9. Nickel (Ni) 10. Tin (Sn) 11. Lead (Pb) 12. Copper (Cu)13. Mercury (Hg) 14. Silver (Ag) 15. Gold (Au) 16. Platinum (Pt)

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How many esters are there with the molecular formula C4H8O2

Chemistry 0

A. 2
B. 3
C. 4
D. 5

Answer & Solution

Option: C
Explanation :There are four esters with the molecular formula C4H8O2.

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Trichlorofluoromethane or CFC-11 is banned by which international protocol/treaty?

Chemistry, World Current Affairs 0

A. Bonn agreement
B. Montreal Protocol
C. Cartagena Protocol
D. Stockholm Convention

Answer & Solution

Option: B
Explanation :Trichlorofluoromethane, also called freon-11, CFC-11, or R-11, is a chlorofluorocarbon. It is a colorless, faint ethereal, and sweetish-smelling liquid that boils around room temperature.
CFC-11 was phased out under the 1987 Montreal Protocol. Despite being the signatory to the Montreal Protocol, and agreeing to phase out production of CFC-11 in 2010, China continued to emit the polluting gas.
Between 40 and 60 per cent of total global CFC-11 emissions originate from Eastern China, reveals study. This is no good news for the ozone layer which is on the road to recovery.

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Which one is called laughing gas?

Pakexammcq Chemistry 0

A. Ferrous chloride (FeCl2)
B. Sulphur dioxide (SO2)
C. Nitrous oxide (N2O)
D. Ferric hydrogen Fe(OH)3

Answer & Solution

Option: C
Explanation :Nitrous oxide (N2O), also called dinitrogen monoxide, laughing gas, or nitrous, one of several oxides of nitrogen, a colourless gas with pleasant, sweetish odour and taste, which when inhaled produces insensibility to pain preceded by mild hysteria, sometimes laughter.Nitrous oxide was discovered by the English chemist Joseph Priestley in 1772; another English chemist, Humphry Davy, later named it and showed its physiological effect.

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Mixing of which material makes rubber more flexible?

Pakexammcq Chemistry 0

A. Graphite
B. Marble powder
C. Sulphur (S)
D. Potassium permanganate (KMNO4)

Answer & Solution

Option: C
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Mixture of two metals is called

Pakexammcq Chemistry 0

A. Alloy
B. Dispersion
C. Fission
D. Diffusion

Answer & Solution

Option: A
Explanation :Metallic bonds can occur between different elements. A mixture of two or more metals is called an alloy. Depending on the size of the atoms being mixed, there are two different kinds of alloys that can form: 1. Substitutional alloy 2. Interstitial alloy

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Which form of phosphorus is used in safety matches?

Pakexammcq Chemistry 0

A. Yellow Phosphorus
B. Blue Phosphorus
C. Red Phosphorus
D. Purple Phosphorus

Answer & Solution

Option: C
Explanation :Pea sized portions of potassium chlorate and red phosphorus are reacted together by striking with a hammer. Smoke, a loud bang and a flash are observed.

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Which one is the lightest gas?

Pakexammcq Chemistry 0

A. Ammonia (NH3)
B. Nitrogen (N2)
C. Carbon Dioxide (CO2)
D. Hydrogen (H2)

Answer & Solution

Option: D
Explanation :Hydrogen and helium, the lightest two gases, weigh so little that helium balloons and hydrogen dirigibles are able to float in the atmosphere. Hydrogen is a diatomic gas, and helium is a monatomic gas. Both hydrogen and helium are lighter than air.

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