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SECTION - A 1. An infertile couple was advised to undergo In vitro fertilization by the doctor. Out of the options given below, select the correct stage for transfer to the fallopian tube for successful results? (a) Zygote only (b) Zygote or early embryo upto 8 blastomeres (c) Embryos with more than 8 blastomeres (d) Blastocyst Stage EXPLANATION:(b) Zygote or early embryo upto 8 blastomeres 2. Given below are four contraceptive methods and their modes of action. Select the  correct match: (a) a)–(i) b)–(ii) c)– (iii) d)–(iv) (b) a)–(ii) b)–(iii) c)–(iii) d) – (i) (c) a)–(iii) b)–(iv) c)–(ii) d)–(i) (d) a)–(iv) b)–(i) c)– (iii) d)–(ii) EXPLAINATION: (c) a) - iii, b) - iv, c) - ii, d) - i 3 Which of the following amino acid residues will constitute the histone core? (a) Lysine and Arginine  (b) Asparagine and Arginine (c) Glutamine and Lysine  (d) Asparagine and Glutamine EXPLANATION:(a) Lysine and Arginine 4 Evolutionary convergence is development of a (a) common set of fu...

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 wri...

 1. (a) Write the molecular formula of the following carbon compounds :  (i) Methane  (ii) Propane (b) Carbon compounds have low melting and boiling points. Why?  explanation: a) molecular formula of methane is CH4 and propane is CH3CH2CH3 b) carbon compounds have the weaker intermolecular force of  interactions hence they have lower boiling and melting points 2. The electrons in the atoms of two elements X and Y are distributed in  three shells having 1 and 7 electrons respectively in their outermost  shells.  (a) Write the group numbers of these elements in the Modern Periodic  Table.  (b) Write the molecular formula of the compound formed when X and  Y combine with each other.  (c) Which of the two is electropositive?  explanation: a) element X has 1 electron in the outermost shell hence it belongs to group 1. while element Y has 7 electrons in the outermost shell to become noble gas and complete its octet it requires o...