Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYEasy

Which of the following options incorrectly describes the possible range of values for the mole fraction ( $x$ ) of a component in a mixture?

$x < 1$

$- 2 \le x \le 2$

$0 \le x \le 1$

$x$ is always non-negative

Definition: Mole fraction ( $x$ ) is the ratio of the number of moles of a specific component to the total number of moles of all components in the solution [Class 12 Chemistry, Ch 1, Sec 1.2.1, Eq 1.4].
Non-negativity: Since the number of moles ( $n$ ) is a count of particles, it must be non-negative ( $n \ge 0$ ). Therefore, mole fraction $x$ is always non-negative ( $x \ge 0$ ).
Upper Limit: The sum of the mole fractions of all components in a mixture is unity ( $1$ ) [Class 12 Chemistry, Ch 1, Sec 1.2.1, Eq 1.7]. Consequently, the mole fraction of any single component cannot exceed 1.
Mixture Constraint: For a mixture (implying at least two components present), $x$ must be strictly less than 1 ( $x < 1$ ) and greater than 0.
Evaluate Option B: The range $-2 \le x \le 2$ implies that mole fraction can be negative or greater than 1, both of which are physically impossible. Thus, this description is incorrect.

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