Which of the following solutions has the highest pH?

Efficiency ($\eta$) is given by the ratio of mechanical advantage (MA) to velocity ratio (VR), expressed as a percentage:

$$\eta = \frac{\text{MA}}{\text{VR}} \times 100\%$$

Given $\text{MA} = 5$ and $\eta = 55.56\% = 0.5556$.

$$\text{VR} = \frac{5}{0.5556}$$ $$\text{VR} \approx 9.00$$

• B. $\mathbf{9}$

22. Mushrooms belong to the kingdom

• Mushrooms are a type of fungus and are classified under the kingdom Fungi.
• B. Fungi

23. An empty plastic bottle floats in water because its

• An object floats in a fluid if its overall density is less than the density of the fluid. An empty plastic bottle contains air, making its average density less than that of water.
• D. density is less than that of the water

24. A substance which increases the rate of a reaction without undergoing chemical change is also

• A catalyst is a substance that increases the rate of a chemical reaction without being consumed or undergoing a permanent chemical change itself.
• C. a catalyst

25. Which of the following types of pollution occur at cities with many vehicles?

• Cities with many vehicles experience air pollution from exhaust fumes, noise pollution from engines and traffic, and land pollution from discarded vehicle parts, oil leaks, and litter.
• B. I, II and III

26. Which of the following solutions has the highest pH?

• The pH scale measures acidity or alkalinity. A higher pH indicates a more alkaline (basic) solution. Among the given options, sodium hydroxide ($\text{NaOH}$) is a strong base, which will have the highest pH. Ammonia is a weak base, while ethanoic acid and hydrochloric acid are acids (weak and strong, respectively), having lower pH values.
• D. $\mathbf{0.5\,mol\,dm^{-3}}$ of sodium hydroxide

27. The statement, to every action there is an equal and opposite reaction is

• This statement is the definition of Newton's third law of motion.
• C. Newton's third law of motion

28. Which of the following statements is true about a car travelling at constant speed on a level ground?

• If a car is travelling at a constant speed on level ground, and assuming it's moving in a straight line, its velocity is constant. Therefore, its acceleration is zero.
• A. Not accelerating

29. Electric current is measured using

• An ammeter is an instrument specifically designed to measure electric current in a circuit.
• B. an ammeter