NCERT Exemplar Class 11 Chemistry Chapter 1 MCQ

(c) AtomicityExplanation:Symbol of an element represents the name along with the number of same atoms in room condition, which is its atomicity, of that element.

(d) 3.0 NExplanation:$ H3PO4 is tribasicSo N = 3M $= 3 ×$1 = 3$.

One mole of sodium

(c) 24.3Explanation:As the given sulphate is isomorphous with ZnSO4.7H2O its formula would be MSO4.7H2O.m is the atomic weight of M, molecular weight of MSO4.7H2O= $(m + 32 + 64 + 126)$ = $(m + 222)$Hence % of M= [(m)/ $(m+222)$] ×$100 = 9$.87(given)Or100 m = $(9.87 m + 222 \times 9.87)$Or 90.$13 m = (222$ × 9.$87)Or m = (222$ × 9.87)/(90.$13) = 24$.3.

(a) KelvinExplanation:The SI unit of temperature is the Kelvin. Although the Celsius temperature scale is also used, it is considered a derived SI unit and is generally used to measure everyday temperatures.In the Kelvin scale, the lowest possible temperature is 0 K. This reading is called absolute zero; however, nothing could possibly ever reach this temperature. Absolute zero, according to the Celsius scale, is approximately minus 273 degrees Celsius. Water boils at 373 Kelvin and freezes at 273 Kelvin.Scientists discovered absolute zero when they figured that as temperature decreases, the volume of a gas also gets smaller. They graphed this relationship and found that for each substance tested, zero volume for each substance would hypothetically occur around minus 273 degrees Celsius, the equivalent of absolute zero.