466: Which one of the following is a non-metallic mineral?
(a) Manganese
(b) Magnesium
(c) Gypsum
(d) Bauxite
467: Assertion (A) :
Dolly was the first cloned mammal.
Reason (R) :
Dolly was produced by in vitro fertilization.
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is not a correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
Explanation:
Dolly was the first cloned mammal developed by British Geneticist Ian Wilmet which was priduced through in vitro fertilization.
468: Which of the following chemicals in automobile-exhaust can cause cancer?
(a) Carbon monoxide
(b) Polycyclic hydrocarbons
(c) Lead
(d) Oxides of nitrogen
469: When one gene controls two or more different characters simultaneously, the phenomenon is called
(a) Apomixis
(b) Pleiotropy
(c) Polyploidy
(d) Polyteny
Explanation:
Pleiotropy : One gene controls two or more different characters simultaneously.
Apomixis : Seed formation without fertilization, i.e. without the union of male and female gamets.
Polyploidy : Presence of more than two sets of chromosomes unlike in Diploids (2 sets of chromosomes present).
Polyteny : Multistranded or polytene chromosome is a giant chromosome present in salivary glands of insects, composed of thousands of copies of DNA parallel to one another due to the process of endomitosis or endoreduplication.
470: In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements:
1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.
2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.
3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.
4. H-CNG makes the fuel less expensive than CNG.
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 and 3 only
(c) 4 only
(d) 1, 2, 3 and 4
Explanation:
Hydrogen-Enriched CNG (H-CNG) is a blend of hydrogen and CNG, the ideal hydrogen concentration being 18%. Hence, Statement 3 is correct.
Compared to conventional CNG, use of H-CNG can reduce emission of carbon monoxide up to 70%,not complete emission. Hence, statement 1 is not correct. It also reduces carbondioxide and hydrocarbon emissions. Hence, statement 2 is correct.
H-CNG also enables up to 5% savings in fuel efficiency. H- CNG also reduces the engines unburned hydrocarbon emissions and speed up the process of combustion.
Source: https://indianexpress.com/article/explained/cng-to-hydrogen-cng-why-switch-and-how-5278356/