The element common to all acids is
Answer: A
Hydrogen is the element common to all acids. An acid is defined as a substance that releases hydrogen ions (H+) in water.
Hydrochloric acid gives HCl → H+ + Cl−, sulphuric acid gives two hydrogen ions, and it is the concentration of those ions that the pH scale measures.
Please log in or register to report this question.
Lactometer is used to determine
Answer: B
A lactometer tests the purity of milk. It is a hydrometer calibrated for milk, and measures specific gravity - normally between 1.028 and 1.034.
Adding water lowers the reading, so the instrument detects dilution, though it will not detect skimming, which raises the density instead.
Please log in or register to report this question.
A chronometer measures
Answer: C
A chronometer measures time - a clock accurate enough to keep time at sea.
John Harrison's marine chronometer, perfected in the 1760s, solved the longitude problem: comparing local noon with the time at a reference meridian gives longitude directly.
Please log in or register to report this question.
Tetraethyl lead is used as
Answer: D
Tetraethyl lead was used as a petrol additive, raising the octane rating and preventing engine knock.
It was phased out worldwide because the lead in the exhaust is a cumulative poison that damages the nervous system, especially in children. India completed the switch to unleaded petrol in 2000.
Please log in or register to report this question.
Wood is the main raw material for the manufacture of
Answer: B
Paper is made chiefly from wood. The wood is pulped - mechanically or with chemicals that dissolve the lignin - to free the cellulose fibres, which are then matted, pressed and dried into sheets.
Softwoods such as pine give long fibres and strength; hardwoods give shorter fibres and a smoother surface.
Please log in or register to report this question.
The naturally occurring anticoagulant in the human blood is -
Answer: B
Heparin is the natural anticoagulant of the blood. It is produced by mast cells and by the basophils, and it works by activating antithrombin, which then inactivates thrombin.
It is what keeps blood fluid inside the vessels. Hirudin is the anticoagulant of the leech, not of human blood.
Please log in or register to report this question.
Which plant is called Herbal-Indian Doctor?
Answer: D
Tulsi, holy basil, is called the herbal Indian doctor.
It is the most widely used plant in Ayurveda, taken for coughs, fever and digestive complaints, and is grown in the courtyard of many Indian homes.
Please log in or register to report this question.
The major ingredient of leather is:
Answer: A
Collagen is the major ingredient of leather - the fibrous protein of animal skin.
Tanning cross-links its fibres so they no longer rot or dry hard. Collagen is also the commonest protein in the body, forming the framework of skin, tendon, bone and cartilage.
Please log in or register to report this question.
Plants mainly receive their nutrients from
Answer: B
Plants take their mineral nutrients from the soil, absorbing nitrogen, phosphorus, potassium and the micronutrients in solution through the root hairs.
Sunlight provides energy and chlorophyll captures it, but neither is a nutrient; the carbon comes from the air as carbon dioxide.
Please log in or register to report this question.
One Joule is equal to
Answer: C
One joule equals 107 ergs.
\[ 1\ \mathrm{J} = 1\ \mathrm{N\,m} = 10^5\ \mathrm{dyne} \times 10^2\ \mathrm{cm} = 10^7\ \mathrm{erg} \]
The erg is the CGS unit of work and the joule the SI unit; the factor comes from converting both the force and the distance.
Please log in or register to report this question.
