Question Discussion & Solution

The correct answer is Thymine and Cytosine.

Key Points

• The pyrimidines in DNA are C & T. In RNA, U replaces T.

• Cytosine (C) formula is C₄H₅N₃O and Thymine (T) formula is C₅H₆N₂O₂.

Additional Information

• Deoxyribonucleic acid, commonly known as DNA, is the hereditary complex molecule present in humans and almost all other organisms.
• The information in DNA (double helix structure) is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
  • DNA has two base pairs, A-T and G-C, attached to a sugar-phosphate backbone.
• DNA is a long molecule that contains our unique genetic code.
  • It holds the instructions for making all the proteins in our bodies and the function of living things.
• In the cell nucleus, the DNA (deoxyribonucleic acid) molecule is packaged into thread-like structures called chromosomes.
  • A chromosome (microscopic structure) is made up of DNA tightly coiled many times around proteins called histones that support its structure.
  • A chromosome has two arms - a p arm (short arm) and a q arm (long arm), joined in the location of the centromere.

• Watson and Crick Proposed the Double Helix structure of DNA with the two strands connected by hydrogen bonds.

Here the pattern is,

Hence, 18T is the correct answer.

Shark, Barracuda and Whale are types of aquatic animals but Humming is a bird.

The correct answer is Lead and Tin.

Key Points

• Soldering is the process of joining two metal objects together by a third soft metal alloy which is called solder.
• Solder is a metal alloy that melts at a lower temperature than the metals being soldered.
• A commonly used alloy is solder, which is an alloy of tin (Sn) and lead (Pb).
• The alloy of tin-lead solder is a mixture of 63% tin and 37% lead. 63/37 solder melts at 183°C.
• So, Alloy of tin (Sn) and lead (Pb) is used for welding electrical wire together.

Additional Information

• Element Tin (Sn) belongs to Group 14 of the periodic table.
  • Atomic Number - 50
  • Atomic Mass  - 118.710 amu.
• Element Lead (Pb) belongs to Group 14.
  • Atomic Number - 82
  • Atomic Mass - 207.2 amu.

According to the question, we have the following diagram,

Hence, Kritika is standing in the south-west direction with respect to her initial position.