Daily NEET MCQ- June 11, 2022 - NEET MCQ

Carbon and hydrogen are detected by heating the compound with copper (II) oxide. In this way, the carbon that is present in the compound will be oxidized to carbon dioxide and hydrogen to water. Carbon dioxide is tested by limewater which develops turbidity, and hydrogen is tested with anhydrous copper sulphate, which turns blue.

Calcium carbonate (CaCO₃) gets precipitated during the detection of carbon and hydrogen. Firstly carbon will react with copper (II) oxide to form copper and carbon dioxide. Then, hydrogen will react with the same copper (II) oxide to form copper and water. After this, the presence of carbon dioxide is tested by reacting it with calcium hydroxide and the product obtained is calcium carbonate, which gets precipitated and water.

Fluorine cannot be detected by lassaigne’s test. Even though lassaigne’s test is used for the detection of halogens, all halogens except fluorine can be detected. This is because, in lassaigne’s test, the sodium extract is treated with silver nitrate. Only in the case of fluorine, the silver fluoride formed is soluble, unlike the others which is insoluble. Thus, the precipitate will not be formed and so, this method cannot be used for fluorine detection.

Conduction involves transfer of heat energy due to vibration of molecules at their positions, convection involves transfer of heat energy by the motion of molecules themselves and radiation involves heat transfer by electromagnetic waves. When water is placed in a very hot pan, the molecules of water in immediate contact with the pan get heated and move away allowing the colder molecules to settle down hence allowing them to touch the pan and get heated. This movement of heated molecules corresponds to convection.

Temperature at the fixed ends of both rods will be the same.
K_S A_S (T-0)/L_S = K_C A_C (100-T)/ L_C
∴ 50*1/2 L_CT = 384* _C (100-T)
⇒ 25T = 38400 – 384T
⇒ T = 63°C.

Heat current is the amount of heat crossing per unit time through any cross section. So, its expression can be written as ΔQ/Δt.

Rice doesn’t show vernalisation. Other crops such as Wheat, Barley and rye which are have two varieties: spring and winter require cold treatment to stimulate photoperiodic response of plants.

Polycarpic plants are plants that set seeds numerous times before senescence. Apple is a polycarpic plant. Sugarbeet, Cabbage & Carrots are some of the common biennials. Biennials are plants that take 2 seasons to complete their lifecycle.

Leaves are the site for perception of light/dark duration. Florigen is responsible for flowering. Shoot apices are modified to flowering apices prior to flowering. The hormone further migrates to stem and roots.

The hypothetical hormone florigen is said to be responsible for flowering in plants. Vernalin is promotes early maturity leading to flowering. ABA is majorly an inhibitor and functions in stressful conditions. Cytokinin stimulates shoots development.