WAEC Past Questions and Answers - Page 3908

19,536.

Simplify \(\frac{2x-1}{3}-\frac{x+3}{2}\)

A.

\(\frac{x+3}{6}\)

B.

\(\frac{x+8}{6}\)

C.

\(\frac{x-11}{6}\)

D.

\(\frac{x-4}{6}\)

Correct answer is C

\(\frac{2x - 1}{3} - \frac{x + 3}{2}\)

= \(\frac{2(2x - 1) - 3(x + 3)}{6}\)

= \(\frac{4x - 2 - 3x - 9}{6}\)

= \(\frac{x - 11}{6}\)

19,537.

Factorize \(6x^2 + 7x - 20\)

A.

(6x - 5)(x + 4)

B.

2(3x-5)(x+2)

C.

(3x+4)(2x-5)

D.

(3x-4)(2x+5)

Correct answer is D

\(6x^2 + 7x - 20\)

= \(6x^2 + 15x - 8x - 20\)

= \(3x(2x + 5) - 4(2x + 5)\)

= \((3x - 4)(2x + 5)\)

19,538.

In a test for non-reducing sugars like sucrose, what is the significance of adding dilute hydrochloric acid to the original sugar solution? To

A.

hydrolyse the non-reducing sugar

B.

accelerate he rate of the reaction

C.

stabilize the medium

D.

sterilize the solution

Correct answer is A

No explanation has been provided for this answer.

19,539.

Biuret’s test is carried out on a food substance to indicate the presence of

A.

vitamins B

B.

fats

C.

proteins

D.

starch

Correct answer is C

No explanation has been provided for this answer.

19,540.

Micronutrients essential for the synthesis of chlorophyll include

A.

iron and potassium

B.

iron and magnesium

C.

magnesium and calcium

D.

magnesium and potassium

Correct answer is B

No explanation has been provided for this answer.