506: Which of the following types of light are strongly absorbed by plants?
(a) Blue and red
(b) Yellow and violet
(c) Violet and orange
(d) Indigo and yellow
Explanation:
Blue and red types of visible light (VIBGYOR) are strongly absorbed by plants where 'photosynthesis process' is active hence called 'Photosynthesis Active Radiation' (PAR).
507: Which one of the following is an active component of oil of clove ?
(a) Menthol
(b) Eugenol
(c) Methanol
(d) Benzaldehyde
508: With reference to the food chains in ecosystems, which of the following kinds of organism is / are known as decomposer organism / organisms?
1. Virus
2. Fungi
3. Bacteria
Select the correct answer using the codes given below.
(a) 1 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3
Explanation:
Fungi and Bacteria are known as decomposer organisms.
509: Malaria fever is caused
(a) Immediately after mosquito bite
(b) Upon disintegration and bursting of red blood cells
(c) When the malaria causing germs reach the liver
(d) Upon release of toxins into blood
510: The most reactive among the halogens is
(a) fluorine
(b) chlorine
(c) bromine
(d) iodine
Explanation:
Halogens belongs to VII A group of periodic table have seven electrons in their outermost orbit. The most reactive halogen is flourine. The reactivity decreases in the order of flourine, chlorine, bromine and iodine.
The halogens are the most reactive because of high electronegativity, small size of atom, high oxidising power and low energy of F-F bond.