Question

The percentage of abundance of three elements \(X, Y\) and \(Z\) in the earth's crust are about \(27.7\), \(8.3\) and \(46.0\) by mass respectively. \(X, Y\) and \(Z\) are:

• A. O, Si, Al
• B. Al, Si, O
• C. Si, Al, O
• D. Al, O, Si

Hint:

The most abundant element in the earth's crust is oxygen, followed by silicon and aluminium. Their approximate abundances are: \[ O \approx 46\%, \quad Si \approx 27.7\%, \quad Al \approx 8.3\% \]

Answer 1

The Correct Option is C

Step 1: Recall the order of abundance in Earth's crust.
By mass: O (46%) > Si (27.7%) > Al (8.3%). This is a standard fact (mnemonic: O-Si-Al leads).

Step 2: Match with X, Y, Z.
X = 27.7% = Si, Y = 8.3% = Al, Z = 46.0% = O. So X, Y, Z = Si, Al, O. \[ oxed{Si,\ Al,\ O} \]