General Science GK Questions with Answers – Page 21

This is false: aluminium has three electrons in its outer shell and loses all three, so its valency is 3.

Cambium lies along the sides of stems and roots and its dividing cells increase their thickness, which is the work of a lateral meristem.

Sodium hydroxide dissolves in water and splits completely into Na+ and OH- ions; the ions carry current and the hydroxide ions make the solution strongly basic.

Powers of lenses in contact simply add, so the combination has a power of 2 + 2 = 4 dioptre, and its focal length is 1/4 m, that is 0.25 m. The power of a lens is the reciprocal of its focal length in metres, P = 1/f, and is…

Parenchyma is the basic packing tissue of plants, and it is also present in both xylem (xylem parenchyma) and phloem (phloem parenchyma).

Oxidising power of the halogens falls as we go down group 17, so iodine is the weakest and fluorine the strongest oxidising agent.

Urea, CO(NH2)2, contains about 46 per cent nitrogen, the highest of any common solid fertiliser, and is the main nitrogen fertiliser used in India.

The primary structure of a protein is simply the linear order of amino acids joined one after another by peptide bonds.

This statement is false: diamond is an electrical insulator because it has no free electrons. In diamond, every carbon atom uses all four of its valence electrons to form strong covalent bonds with four other carbon atoms in a rigid three-dimensional network.

Platelets, or thrombocytes, release the factors that start blood clotting at a wound. Platelets are tiny cell fragments made from large cells called megakaryocytes in the bone marrow; a healthy adult has about 1.5 to 4.5 lakh of them per cubic millimetre of blood.

The standard hydrogen electrode has a real, non-zero potential; it is only assigned the value zero by convention. The absolute potential of a single electrode cannot be measured, because any measurement needs a second electrode to complete the circuit.

It states that when hot and cold bodies are mixed in an insulated system, heat lost by the hot body equals heat gained by the cold body.

Dengue virus is a flavivirus, an RNA (ribonucleic acid) virus of the family Flaviviridae. Dengue is spread mainly by the bite of the female Aedes aegypti mosquito, which breeds in clean, stagnant water and bites during the day.

Metal blocks X-rays far more strongly than body tissue, so it spoils the picture. An X-ray image is a shadow picture.

The name comes from the Greek words for naked and seed: gymnosperms bear seeds that are not enclosed in a fruit, and most of them are woody, evergreen trees.

Clean sand is made almost entirely of quartz, which is silica or silicon dioxide, and silica is the main ingredient of glass.

A magnetic field pushes a moving charge sideways, and the push on a negative charge is opposite to that on a positive one, so the two kinds bend away from each other.

In rusting, iron combines with oxygen in the presence of water to form hydrated iron oxide, and the addition of oxygen is oxidation.

When muscles run short of oxygen, the pyruvate formed from glucose is converted into lactic acid instead of being broken down fully.

Water gas is a mixture of carbon monoxide and hydrogen, made by passing steam over red-hot coke. The reaction is C + H2O → CO + H2, carried out at about 1,000 degrees Celsius.