Question
Which of the following does not give effervescence with
sodium carbonate?Solution
Effervescence with sodium carbonate (Na₂CO₃) is due to the release of carbon dioxide (CO₂) gas when it reacts with an acid: 2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂↑ This reaction occurs only if the compound has acidic hydrogen strong enough to liberate CO₂ from carbonate. Phenol does not give effervescence because: It is a very weak acid and does not react with carbonates or bicarbonates to release CO₂. It cannot liberate CO₂ gas due to the stability of the phenoxide ion and weak acidity.
(a – 2) 2 + (b + 6) 2 + (c – 1) 2 = 0, then find the value of a + b – c.
Length of each side of a rhombus is 13 cm and one of the diagonal is 24 cm. What is the area (in cm2) of the rhombus?
If (x 2 = 6x – 9), then find the value of [x³ + (x⁴/9)][5 - x³]
If [x + (1/x)] = 3, find [x2 + (1/x2)].
If x + y = 12 and x² + y² = 74, find xy.
If a3 + b3 = 6240 and a + b = 30, then find the value of {(a + b)2 – 3ab}
- If x² - 2x + 1 = 0, then find the value of (x² + x⁻²)(x³ + x⁻³).
(x + 4) 2 + (y – 1) 2 + (z + 2) 2 = 0, then find the value of 2x - 3y + z.
If x = 19, then the value of x5 - 20x4 + 20x3 - 20x2 + 20x - 1 is
