General Science Chemistry MCQ

[D] Ne

Notes:

Neon is used in neon discharge lamps and advertising signs because the neon lights are visible from long distances. Since the light of neon signs has a better penetrating power through fog and mist, the neon signs are also used in beacon lights for the safety of air and sea navigation.

[D] Osmium

Notes:

The measured densities of iridium and osmium seem to indicate that osmium is slightly denser than iridium, so osmium has generally been credited with being the heaviest known element. It is the densest naturally occurring element, with a density of 22.59 g/cm³.

[A] Hydrogen

Notes:

The Sun is composed primarily of hydrogen and helium; they account for 74.9% and 23.8% of the mass of the Sun in the photosphere, respectively. All heavier elements, called metals in astronomy, account for less than 2% of the mass, with oxygen (roughly 1% of the Sun’s mass), carbon (0.3%), neon (0.2%), and iron (0.2%) being the most abundant.

[B] Calcium

Notes:

Among the given options, calcium is the most reactive since it has the greatest tendency to lose electrons and form positive ions. However, calcium is less reactive than potassium and sodium.

[B] Sodium carbonate

Notes:

Sodium carbonate, Na2CO3, (also known as washing soda, soda ash and soda crystals) is mainly used as detergent powder. It is used to remove stubborn stains from laundry and is an essential component in most homemade laundry detergent for powder, liquid, or single pod formulas. It is often used in commercial detergent mixtures as well to treat hard water.

[C] Tartaric acid

Notes:

Tartaric acid is a white crystalline organic acid that occurs naturally in many plants, most notably in grapes. Its salt, potassium bitartrate, commonly known as cream of tartar, develops naturally in the process of winemaking.

[B] Difluoro Dichloro Methane

Notes:

Dichlorodifluoromethane (R-12), is a colourless gas, and usually sold under the brand name Freon-12, is a chlorofluorocarbon halomethane (CFC), used as a refrigerant and aerosol spray propellant. Complying with the Montreal Protocol, it is prepared by reacting carbon tetrachloride with hydrogen fluoride in the presence of a catalytic amount of antimony pentachloride. This reaction also produces trichlorofluoromethane (CCl3F), chlorotrifluoromethane (CClF3) and tetrafluoromethane (CF4).

[A] Nitrous oxide

Notes:

Nitrous oxide (N2O) and methane (CH4) are the two major greenhouse gasses (GHG) emitted by agricultural activities. N2O accounts for around 8% of the warming impact of current human GHG emissions. Agricultural activities that directly increase N2O emissions are: fertilization, application of manure or other organic materials, retention of crop residues, production of nitrogen-fixing crops and forages, and cultivation of soils with high organic matter content. Irrigation, drainage, tillage practices and fallowing of land also increase N2O emission.

[A] Methyl salicylate

Notes:

Iodex has the characteristic odour of Methyl salicylate, an organic ester naturally produced by many species of plants, particularly wintergreens. It is used in high concentrations as a rubefacient and analgesic in deep heating linments to treat joint and muscular pain.

[A] Silk

Notes:

Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity (sericulture).