RRB Group D GK Questions 2026

Cobalt-60 is an artificial radioisotope that emits penetrating gamma rays and has a half-life of about 5.27 years, which makes it a convenient and long-lasting source for irradiation plants.

Iodine forms a deep blue-black complex with the long coiled chains of amylose in starch, and this colour change is the standard classroom and field test for starch.

Codex Alimentarius is Latin for food code, and the Commission of that name draws up model standards, codes of practice, and limits for additives, contaminants and pesticide residues, which member countries use when writing their own food law and which serve as the reference in international food trade.

That Act consolidated several scattered food laws, the most important of them the Prevention of Food Adulteration Act of 1954, into a single statute and created one authority to lay down science-based standards for food, regulate its manufacture, storage, distribution, sale and import, and licence food businesses; its headquarters is…

Lumps of calcium carbide hidden in a crate of mangoes react with the moisture in the air and release acetylene gas, which forces the fruit to colour quickly, though the pulp inside stays unripe and tasteless.

Indian food standards divide preservatives into two classes. Class I preservatives are the natural ones that cooks have always used, and no limit is placed on the quantity: common salt, sugar, dextrose, spices, vinegar or acetic acid, honey and edible vegetable oils.

In lyophilisation the material is first frozen and then placed under a strong vacuum, so that the ice changes directly into vapour without passing through the liquid state.

Pasteurisation is not sterilisation: it is a mild heating that kills disease-causing organisms such as Mycobacterium tuberculosis, Salmonella and Brucella and most spoilage bacteria, while leaving the taste and nutritive value of milk largely unchanged.

Khesari dal, botanically Lathyrus sativus and also called grass pea, is a hardy pulse that survives drought and is therefore sometimes mixed with arhar dal or besan.

Argemone mexicana, the prickly poppy known in India as satyanashi, has seeds that look very like mustard seeds, so its oil is a classic adulterant of mustard oil.

A harvested fruit is still a living tissue that keeps respiring, using up its own sugars and acids and giving off heat, carbon dioxide and ethylene.

Alfalfa, chickpea and clover are legumes, and legumes fix nitrogen. Plants of the legume family (Fabaceae) carry root nodules that house Rhizobium bacteria.

An insulator is charged by friction: rubbing transfers electrons from one surface to another, and because electrons cannot move through an insulator, the charge stays where it is as static electricity.

In glass, violet light has the shortest wavelength and the highest refractive index, so it bends the most; dispersion is a result of refraction.

By Newton's second law, F = m × a, so a = F ÷ m = 5 N ÷ 10 kg = 0.5 m/s².

In the cytoplasm, glucose is split by glycolysis into two molecules of pyruvate, releasing a small amount of energy as ATP.

Living things are built up level by level: molecules such as proteins form cells, cells form tissues, tissues form organs, organs form organ systems, and these together make an organism.

pH falls, not rises, as hydrogen ion concentration rises, so a more acidic solution has a lower pH. pH is defined as the negative logarithm of the hydrogen ion concentration: pH = −log[H⁺].

Treating rock phosphate, which is insoluble calcium phosphate, with sulphuric acid gives superphosphate of lime, a fertiliser whose phosphorus plants can absorb.

A nitrogen molecule, N₂, is diatomic, not triatomic; its two atoms are joined by a triple bond, and the molecules attract each other only weakly.