Given: 7, 14, 56, 448, 2688, 26880

Logic: The pattern is multiplying by increasing numbers: ×2, ×4, ×6, ×8, ×10.

7 × 2 = 14

14 × 4 = 56

56 × 6 = Should be 336 Not 448

336 × 8 = 2688

2688 × 10 = 26880

Therefore, 448 does not follow the expected pattern.

Thus, the correct option is (a) 448

The correct answer is (c) Copper

Explanation:

In the reactivity series, metals are arranged according to their ability to displace other metals from solutions and react with water and acids. Iron is more reactive than copper because copper is placed lower in the reactivity series, indicating that iron can displace copper from its compounds.

Information Booster:

• Reactivity Series: The reactivity series is a list of metals arranged in the order of their reactivity, from the most reactive (potassium) to the least reactive (platinum and gold).
• Iron is placed above copper in the reactivity series, meaning iron reacts more readily with oxygen and acids than copper.
• Iron reacts with acids to form salts and hydrogen gas, while copper does not react with dilute acids under normal conditions.

Correct Answer is: Data in either statement I alone or statement II alone are sufficient to answer the question.

Five people A, B, C, D and E are sitting in a straight row, facing north. Who sits second to the right of A?

Statement:

I. The number of people sitting to the right of A is equal to the number of people sitting to the left of A. One person sits between A and B. D sits to the immediate left of B.

II. E sits at the extreme left end of the row. Only one person sits between E and A. B sits to the immediate right of D.​​

Data in either statement I alone or statement II alone are sufficient to answer the question.

Thus, correct option is (d).

Given:

tan 2A = cot(A-18°)

Formula used:

Tan A = Cot B

A + B = 90°

Solution:

tan 2A = cot(A-18°)

2A + A - 18° = 90°

3A = 108°

A = 36°

Given: 9 4 6 6 4 9 5 9 4 7 8 9 1 6 4 9 6 4 9

Logic: Not 6 | 4 | Not 9

Two times does 4 appear in the following sequences, where it is neither preceded by 6 nor immediately followed by 9.

Thus, correct option is (c).

Correct Answer:(d) Chlorine

Explanation:

Chlorine is the most commonly used substance added to tap water for disinfection purposes. It is effective in killing harmful microorganisms such as bacteria, viruses, and protozoa that may be present in untreated water. Chlorination ensures that the water is safe for human consumption and helps prevent waterborne diseases like cholera, typhoid, and dysentery.

Information Booster:

• Chlorine is added in the form of chlorine gas, sodium hypochlorite, or calcium hypochlorite.

• The process is known as chlorination.

• Recommended residual chlorine in drinking water: 0.2–0.5 mg/L.

• Excessive chlorine can affect taste and smell but is controlled within safe limits.

• It's widely used in municipal water treatment plants across the world.

Additional Information:

• Iron –Not used for disinfection; its presence in high amounts is considered a contaminant.

• Fluoride – Added to prevent dental cavities, not for killing microbes.

• Calcium – Important for bone health, but not a disinfectant.

The Correct Answer is C. Lemon.

Explanation:

Lemon is not rich in iron. While it is a good source of vitamin C, which helps in the absorption of iron from plant-based foods, it does not contain significant amounts of iron itself.

Key Points:

• Lemon: Contains vitamin C, which aids in the absorption of iron but does not provide iron itself.

Additional Information:

• Spinach: A rich source of iron, particularly non-heme iron (plant-based iron).
• Red Meat: Contains heme iron, which is easily absorbed by the body.
• Peas: A good source of iron, especially for vegetarians.