Test : Chemistry - 4 - NDA MCQ

Bhopal gas tragedy occured on the night of 2–3 December 1984 at the Union Carbide India Limited (UCIL) pesticide plant in Bhopal, Madhya Pradesh. Over 500,000 people were exposed to methyl isocyanate (MIC) gas and other chemicals leaked from UCIL.

The Chlorofluro carbon formed by chlorine, fluorine and carbon. They are often used as refrigerants, solvents, and for the manufacture of spongy plastics. It is the primary reason for depletion of the ozone layer.

Oxygen atom is joined by double covalent bond.

Mercury has the lowest melting point. Mercury has a melting point of -37.89F.
 

Sodium bicarbonate is commonly known as baking soda. It is a chemical compound with the formula NaHCO3.

Sodium hydroxide reacts with metal to release hydrogen gas. The metal takes the oxygen atom from sodium hydroxide, which in turn takes the oxygen atom from the water, and releases the two hydrogen atoms. The reaction thus produces hydrogen gas.

Calcium hydroxide base is present in lime water.

Redox reaction is the reaction in which oxidation and reduction occurs simultaneously. Rust of iron is nothing but hydrate of iron oxide and iron (III) oxide -hydroxide.
 

A cation is a positively-charged ion, while an anion is negatively charged. Sulphate is an anion.

Smog is a type of air pollutant. It  is composed of nitrogen oxides, sulphur oxides, ozone, smoke or particulates among others (less visible pollutants include carbon monoxide, CFCs and radioactive sources).
 

The noble gases make a group of chemical elements with similar properties under standard conditions, they are all odourless, colourless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and the radioactive Radon (Rn). 

High resolution photographic plates having a coating of exceedingly fine-grained photosensitive emulsions with sub microscopic crystals of silver bromide in gelatin. 

Paddy fields are a major source of atmospheric methane .

Polytetrafluoroethylene (PTFE) is usually known as Teflon. This is especially used for making a non-stick surface coating for utensils.

Nitrous Oxide (N2O) is also known as laughing gas. It is a colourless gas with a sweet odour and taste.  It is also used as the anesthetic gas. 

Nila thotha is a compound of Copper and sulphate. Its chemical formula is CuSO4.5H2O.

The organic compounds are a large class of chemical compounds in which one or more atoms of carbon are covalently linked atoms of other elements, most commonly Hydrogen, Oxygen or Nitrogen.

Stainless steel alloy with a minimum of 10.5% Chromium content by mass. The presence of Chromium protects steel from corrosion, rust and make it high-temperature resistance. 

During hydrogenation, the vegetable oils are reacted with hydrogen gas . A nickel catalyst is used to speed up the reaction. The double bond is converted to single bond in the reaction. In this way, the unsaturated fats can be made into saturated fats. 

Sulphur hexafluoride (SF6) is an inorganic, colourless, odourless and non-flammable compound. SF6 has an octahedral shape. It has 12 electrons around the central Sulphur atom. This means there are six electron pairs arranged in an octahedral shape.