Question Discussion & Solution

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.

Least possible diagram is:

I. Some car are Maruti. → True

II. No Ciaz is a Maruti. → False

CONCEPT:

Metals Have Luster:

• Metals, in their pure state, have a shining surface. This property is called metallic luster.
• All the metals have a luster and shiny property except Lead.
• If we polish metals most of them having a reflecting surface i.e. Gold, Silver, etc.

EXPLANATION:

• When light shines on a lustrous metal, the loosely bound electrons reflect incoming light, giving the metal a shiny appearance. Therefore option 3 is correct.

The correct answer is Camel.

Key Points

• The state animal of Rajasthan is Camel.
• Camel was adopted as the state animal of Rajasthan to control the decreasing number of camels in the state. 
• It was adopted in 2014 by the Rajasthan state government.

Additional Information

• State Bird: Great Indian Bustard.
• State Animal (Wildlife) - Chinkara
• State Flower: Rohida.
• Chinkara is also the official animal of Rajasthan.
• National Park: Sariska National Park, Ranthambore National Park, Desert National Park, and Keoladeo Ghana National Park.
• Geographical indication: Kota Doria, Kathputlis, Blue pottery, Molela, clay work, Sanganeri Hand Block Printing, Phulkari, Bikaneri Bhujia, Bagru hand block print, Thewa artwork, Makrana marble.

The given group is all the Forms of energy. Leaping frog is mechanical energy, melting ice cream is thermal energy, and Radio wave is a type of Electromagnetic energy.

Out of the given alternatives lightning is a type of electrical energy.