Question Discussion & Solution

The correct answer is Calcium Carbonate.

Key Points

• The chief component of the nacre that constitutes the pearl is aragonite (CaCO₃).
• Nacre also contains a small amount of conchiolin, a hornlike organic substance (albuminoid) that is the main constituent of the mollusc's outer shell.
• Pearl also contains Magnesium Carbonate(MgCO₃) along with Calcium Carbonate.

Additional Information

• Calcium carbonate is a common substance found in rocks as the minerals calcite and aragonite and is the main component of eggshells, snail shells, seashells, and pearls. 
• The Molar Mass of Calcium Carbonate is 100.0869 g/mol.
• Melting point: 825 °C.

The correct answer is Bone.

• Bone:
  • Bone is living, growing tissue. It is made mostly of collagen, a protein that provides a soft framework, and calcium phosphate, a mineral that adds strength and hardens the framework.
  • Osteoporosis, or porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased risk of bone fractures.

Additional Information

• Heart:
  • A large proportion of cardiovascular disease is due to atherosclerosis.
  • In atherosclerosis, the walls of your arteries become thick and stiff because of the build up of fatty deposits called plaques. 
• Glomerulonephritis is a group of diseases that injure the part of the kidney that filters blood.
• Asthma, Chronic obstructive pulmonary disease (COPD), Pneumonia are common lung diseases.

Concept:

• Atoms are made up of subatomic particles - electrons protons and neutrons.
• In the center of an atom, a nucleus is present which contains protons and neutrons together known as nucleons.
• The mass of an atom is most concentrated at the center of the atom, i.e. the nucleus.

​Electrons:

• Discovered by Sir J.J Thomson in the year 1897.
• Previously named as cathode rays as they were supposed to be emitted from the cathode.
• They are deflected towards the positive side.
• They have high kinetic energy.
• They are deflected by an electric and magnetic field.
• It has a negative charge of

  \(charge=1.602\times10^{-19} coulombs \)
\(mass={1\over 1837}\times 9.107\times 10^{-28}g\)

Protons:

• Discovered by Goldstein.
• Depicted first as positive rays because it seemed to emerge from the anode.
• Mass of a proton is

 \(1.670 \times 10^{- 24}g\)

\(Charge=1.602\times 10^{-19} coulombs\)​

Explanation:

• Rutherford's discovery led to the discovery of nucleus.
• He found out that most of the mass of the nucleus is situated in its centre and contains the positively charged particles protons.
• The atom is otherwise empty and as electrons have negligible mass, the mass of an atom should be equal to the sum of mass of protons present in it.
• However, it was seen that in Helium, there are only two protons, so its mass should be twice the mass of each proton = \(2\times 1.008 a.m.u\).
• Experimental results revealed that it has a mass of 4.003a.m.u.
• Hence, it was concluded that the nucleus has particles containing no charge but mass almost equal to that of a proton.
• This was established by scientist James chadwick in 1932.

Additional Information

Rutherford's gold foil experiment: 

• He discovered the atomic nucleus and gave us an atomic model.
• He directed alpha particles towards a metal sheet.
• He saw that most of the alpha particles, which are positively charged particles, are not getting deflected.
• Most of the alpha particles emerged undeflected.

• Therefore, he concluded that most of the mass of the nucleus is situated in its centre and contains the positively charged particles protons.
• Electrons revolve around the nucleus in certain orbits.

Five students – M, Q, U, X, and Z are compared.

1. Weight of Z is less than only two students. _ > _ > Z > _ > _

2. Weight of Q is greater than Z and Weight of Q is less than only U.

U > Q > Z

From 1 and 2, we get:

U > Q > Z > M/X > M/X

• Apiculture is the technique of scientific rearing of honey bees in a specially designed wooden box.
• The essential elements for beekeeping are smoker, safety dress, moveable hive, honey extractor and hive tool.
• Sericulture is the process of rearing of silkworms to produce raw silk.
• Sericulture is the production of raw silk by means of raising caterpillars (larvae), those of the domesticated silkworm.
• Silk is a continuous filament within each cocoon.

Additional Information