10 COMMON QUESTION ON CHEMISTRY

Question 1

In known elements, the maximum number is of ________?

  metals

  non-metals

  metalloids

  none of above

It's 'metals '
A metal is a material (an element, compound, or alloy) that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. About 91 of the 118 elements in the periodic table are metals.

Question 2

Which of the following is not a natural polymer?

  Wool

  Silk

  Cotton

  Teflon

It's 'Teflon '
Natural polymers occur in nature and can be extracted. They are often water-based. Examples of naturally occurring polymers are silk, wool, DNA, cellulose, cotton and proteins.

Question 3

Which one of the following petroleum refinery products has the lowest boiling point?

  Kerosene

  Gasoline

  Diesel

  Lubricating oil

It's 'Lubricating oil '
lubricating oil is the most commonly used lubricant because of its wide range of possible applications. The two basic categories of lube oil are mineral and synthetic. Mineral oils are refined from naturally occurring petroleum, or crude oil. Synthetic oils are manufactured polyalphaolefins, which are hydrocarbon-based polyglycols or ester oils.

Question 4

The photoelectric effect is described as the ejection of electrons from the surface of a metal when _____?

  It is heated

  It is placed in strong electric field

  Electron of suitable velocity impinge on it

  Light of suitable wavelength falls on it

It's 'Light of suitable wavelength falls on it '
The photoelectric effect refers to the emission, or ejection, of electrons from the surface of, generally, a metal in response to incident light. Energy contained within the incident light is absorbed by electrons within the metal, giving the electrons sufficient energy to be 'knocked' out of, that is, emitted from, the surface of the metal.

Question 5

Which one of the following chemical compounds is responsible for the stimulation of tear glands by the onion?

  phosphate compound

  nitrate compound

  sulphide compound

  chloride compound

It's 'sulphide compound '
When an onion is cut, certain (lachrymator) compounds are released causing the nerves around the eyes (lacrimal glands) to become irritated. These compounds consist of methionine and cystine that are part of the amino acid family. When an onion is sliced or diced, the onion's cells release these compounds into the air. When this occurs, "enzyme" works to alter the amino acids into lachrymator compounds. This form of sulfuric acid irritates the nerves around the eyes making them tear.

Question 6

The gas used to extinguish fire, is ____?

  neon

  nitrogen

  carbon dioxide

  carbon monoxide

It's 'carbon dioxide '
Fire needs three elements to prosper: fuel, oxygen and heat. The most common extinguishing agents like water, carbon dioxide, dry chemical and foams attack the fire physically to deprive the fire of one or more of the three critical elements needed for propagation. Halon differs in the way it puts out the fire.

Question 7

The charcoal used to decolourise raw sugar is __________?

  animal charcoal

  sugar charcoal

  coconut charcoal

  wood charcoal

It's 'coconut charcoal '
Charcoal is used as a decolourizing agent as it can adsorb colouring matter. It is used for decourizing sugar solutions, organic preparations, alcohol and petroleum products.

Question 8

Diamond, graphite, and fullerenes all forms of carbon, are examples of _______?

  catalysts

  isotopes

  structural isomers

  allotropes

It's 'allotropes '
Allotropes are different structural modifications of an element. The atoms of the element are bonded together in a different manner.

Question 9

A polymer which is used for making ropes and carpet fibres is ________.

  Polyacetylene

  Polypropylene

  Polyacrylonitrile

  PVC

It's 'Polyacetylene '
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging and labeling, textiles (e.g., ropes, thermal underwear and carpets), stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes

Question 10

What among following is used to produce artificial rain?

  copper oxide

  carbon monoxide

  silver iodide

  silver nitrate

It's 'silver iodide '
Artificial rain is produced by spraying clouds with substances like Silver Iodide (costly) or cheaper ones like solid carbon dioxide (dry ice) or even finely powdered Sodium Chloride.