1. (a) Draw two different possible structures of a saturated hydrocarbon having four carbon atoms in its molecule. What are these two structures of the hydrocarbon having same molecular formula called? Write the molecular formula and the common name of this compound. Also, write the molecular formula of its alkyne.
OR
(b) (i) Write the molecular formula of benzene and draw its structure.
(ii) Write the number of single and double covalent bonds present in a molecule of benzene.
(iii) Which compounds are called alkynes?
Explanation: two possible structures of hydrocarban
these structures are called isomers. isomers have the same molecular formula but different structural arrangements.
the molecular formula of the alkyne is
OR
i) the molecular formula of benzene is C6H6
ii) there are double bonds and nine single bonds in benzene.
iii) Alkynes are organic molecules made of the functional group carbon-carbon triple bonds and are written in the empirical formula of Cn H2n−2. They are unsaturated hydrocarbons. alkynes use the ending –yne.
2. (a) Mention one function of each of the following organs in the human male reproductive system :
(i) Testis
(ii) Scrotum
(iii) Vas deferens
(iv) Prostate gland
(b) Name the type of germ cell that (i) is motile, and (ii) stores food.
Explanation: a) function of
i) Testis produces reproductive cells by a process called spermatogenesis and also secretes the male sex hormone – testosterone.
ii) The scrotum performs the key role of holding the testes, blood vessels, nerves and epididymides. Since sperm must be held at a constant temperature, the scrotum functions to keep the testes at a constant level of warmth.
iii)Vas deferens help in the transmission of mature sperms.
iv) Prostate glands help in the production of the fluid that nourishes and activates the spermatozoa to swim.
b) The male germ cell is sperm and it is motile. The female germ cell is the ovum that store food.
3. (a) Three resistors R1, R2 and R3 are connected in parallel and the combination is connected to a battery, an ammeter, a voltmeter and a key. Draw a suitable circuit diagram to show the arrangement of these circuit components along with the direction of the current flowing.
(b) Calculate the equivalent resistance of the following network :
Explanation: a)
b)
4. (a) (i) Define Electric Power and write its SI unit.
(ii) Two bulbs rated 100 W; 220 V and 60 W; 220 V are connected in parallel to an electric mains of 220V. Find the current drawn by the bulbs from the mains.
explanation: a) i) The rate at which electric energy is dissipated or consumed in an electric circuit.
S.I. unit - watt / V. A / joule per second
5. (a) Name the group of organisms which form in the first trophic level of all food chains. Why are they called so?
(b) Why are human beings most adversely affected by bio-magnification?
(c) State one ill-effect of the absence of decomposers from a natural ecosystem.
explanation: a) This first trophic level contains only producers.
Producers are those who can able to form their own food by themselves, in simple words they are autotrophic organisms. Examples like green plants. They will come to the first trophic level of any food chain, as they produce food on their own.
b) Human beings occupy the top place of most trophic level and we know that the concentration of harmful chemicals increase as we go above the trophic level. Therefore human beings are most adversely affected by biological magnification.
c) In the absence of decomposers, the dead bodies of plants and animals would keep lying as such and the elements of plant and animal bodies would never be returned to their original pool like soil, air and water. The cycling process of life and death would be disrupted. The nutrient pool will not be replenished and would exhaust soon.
for part I of important questions follow the article mentioned below:
https://psychologicalblogspot.blogspot.com/2022/12/important-questions-for-cbse-class-10.html
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