The correct answer is (c) Electron

Explanation:

• An electron is a subatomic particle that carries a negative charge. It orbits the nucleus of an atom and is involved in chemical reactions and electricity.
• The negative charge of an electron is equal in magnitude but opposite in sign to the positive charge of a proton.
• Electrons play a crucial role in the formation of ions and the electrical properties of matter.

Information Booster:

• Electrons are fundamental particles found in atoms, along with protons and neutrons. They have a mass approximately 1/1836th of that of a proton and are essential for the chemical properties of elements.
• The charge of an electron is exactly -1.602 × 10⁻¹⁹​ Coulombs, which is a standard value.
• Electrons are located in electron clouds or orbitals around the nucleus, which contains protons and neutrons.
• Discovered by J.J. Thomson in 1897​
• The behavior of electrons is described by quantum mechanics, which governs their movement, interaction with light, and ability to form bonds with other atoms.

Additional Knowledge:

Proton:

• Discovered by Ernest Rutherford in 1917.
• A proton is a positively charged particle found in the nucleus of an atom. Its charge is +1.602 × 10^−19​ Coulombs, which is the opposite of the electron's negative charge. Protons, together with neutrons, make up most of the mass of an atom.

Neutron:

• A neutron is a neutral particle, meaning it carries no charge. Discovered by James Chadwick in 1932.
• It is found in the nucleus of an atom and has a mass roughly equal to that of a proton.
• Neutrons play a vital role in stabilizing the nucleus by balancing the repulsive forces between positively charged protons.

Positron:

• A positron is the antimatter counterpart of the electron.
• Theoretical Prediction: Paul Dirac (1928)
• Experimental Discovery: Carl Anderson (1932)
• It carries a positive charge and has the same mass as an electron.
• When a positron encounters an electron, they annihilate each other in a process known as pair annihilation, releasing energy in the form of gamma rays.

Correct Answer: (d) Ag₂S

Explanation:

The black coating that forms on silver jewellery is primarily due to the formation of silver sulfide (Ag₂S).

This occurs when silver reacts with sulfur or sulfur compounds in the environment, leading to tarnishing.

The presence of moisture and air can accelerate this reaction, resulting in the characteristic black appearance.

Information Booster:

Silver sulfide forms when silver reacts with sulfur compounds.

Tarnishing is accelerated by humidity, exposure to air, and environmental pollutants.

Proper cleaning methods, such as using a silver polish, can help restore tarnished silver.

Anti-tarnish strips can be used to minimize tarnishing when storing silver items.

Additional Information:

• Ag₂CO₃ (silver carbonate): it decomposes to silver oxide and carbon dioxide upon heating.
• AgNO₃ (silver nitrate): A soluble silver salt used in various applications, including photography.
• AgCl (silver chloride): This compound forms a white precipitate when silver is exposed to chlorine.

Given:

The lengths of the diagonals of a rhombus are 12 cm and 16 cm

Formula Used:

The correct answer is (b) Non-uniform motion.

Explanation:

Non-uniform motion occurs when the speed or direction of an object changes during its movement. In this case, the car slows down and eventually stops, indicating a change in speed, which is a key characteristic of non-uniform motion.

Information Booster:

• Non-uniform motion involves a change in speed or direction during the motion.
• In non-uniform motion, an object does not maintain a constant velocity.
• The car slowing down and stopping is an example of negative acceleration or deceleration, which occurs in non-uniform motion.
• Non-uniform motion is often observed in everyday life, such as a car decelerating or accelerating.

Additional Knowledge:

• (a) Uniform motion: This type of motion occurs when an object moves at a constant speed along a straight path, which does not apply to the car in this case as its speed changes.
• (c) Circular motion: This type of motion refers to movement along a circular path, not relevant to the straight path of the car described.
• (d) Periodic motion: Periodic motion involves motion that repeats in regular intervals, such as a pendulum, which does not apply to the car's movement.

Given:

The sum of all interior angles of a polygon = 2700°

Formula used:

Logic: The arrow show the movement of the letter or symbol in a logical way.

The complete figure series is shown below:

Thus, the correct option is (d)

Given:

Cost price (CP) of the fan = Rs. x

List price (LP) = CP + 22% of CP = 1.22 × CP

Discount offered = 15% of LP

Profit earned = Rs. 111

Formula Used:

Selling price (SP) = LP - Discount

Discount = 15% of LP = 0.15 × LP

Profit = SP - CP

Solution:

Let the cost price be Rs. x.

List price (LP) = 1.22 × x

Discount = 0.15 × 1.22 × x

Selling price (SP) = LP - Discount

SP = 1.22 × x - 0.15 × 1.22 × x

SP = 1.22 × x (1 - 0.15)

SP = 1.22 × x × 0.85

SP = 1.037 × x

Given profit = Rs. 111

Profit = SP - CP

=> 111 = 1.037 × x - x

=> 111 = 0.037 × x

=> x = 111 / 0.037

=> x ≈ 3000

List Price (LP) = 1.22 × x

LP = 1.22 × 3000

LP = 3660

The list price of the fan is Rs. 3660.

Correct Answer is: 30

​Logic: Count the total number of squares in the given 4 × 4 grid systematically.

Counting Individual Squares:

1 × 1 squares: There are 16 small squares (4 rows × 4 columns).

2 × 2 squares: There are 9 squares (3 rows × 3 columns).

3 × 3 squares: There are 4 squares (2 rows × 2 columns).

4 × 4 squares: There is 1 big square covering the entire grid.

Total Count: 16 + 9 + 4 + 1 =30

Thus, the correct option is:(b) 30

Logic: 1st letter + 4 = 2nd letter, 2nd letter + 2 = 3rd letter.

Let's check by options;

Option (a): FHJ (Does not follow)

F + 2 = H, H + 2 = J

Option (b): EIK (Follow)

E + 4 = I, I + 2 = K

Option (c): CGI (Follow)

C + 4 = G, G + 2 = I

Option (d): AEG (Follow)

A + 4 = E, E + 2 = G

So, (b), (c), d) follows the same logic except option (a).

Thus, the correct answer is (a).