EASY
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The chemical formula of calcium oxide is:

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Important Questions on Atoms and Molecules

EASY

A solution of a substance 'X' is used for whitewashing.

(a) Name the substance 'X' and write its formula.

(b) Write the reaction of the substance with water.

HARD
The formulae of an oxide of an element M is MO. The formulae of its phosphate is
MEDIUM

Find the empirical formula and the molecular formula of an organic compound from the data given below:

C = 75.92%,  H = 6.32%  and  N = 17.76%

The vapour density of the compound is 39.5.  [C = 12,  H = 1,  N = 14]

MEDIUM
The element ‘X’ has an electronic configuration 2,8,3. Element ‘Y’ has an electronic configuration 2,8 7. The chemical formula of the compound formed when they react is
MEDIUM
An organic compound contains 60%C; 4.48%H and 35.5% O. Its empirical formula is
MEDIUM
Write chemical formula of Magnesium Chloride.
EASY
Molecular formula of a compound is C6H18O3. Find its empirical formula.
MEDIUM
An element ‘P’ which belongs to 13th group of the periodic table and another element ‘Q’ belongs to 16th group. The formula of the compound formed if they react with each other is:
MEDIUM
If the vapour density of the carbon containing gaseous substance is 13, which of the following is its molecular formula?
MEDIUM
The molecular formula of chloride of a metal M is MCl2. The molecular formula of an oxide of M will be:
MEDIUM
An element X with atomic number 13 combines with another element Y of atomic number 17. The formula of the compound formed and the nature of the bond will be:
MEDIUM
The empirical formula and molecular mass of a compound are CH2O and 180 g respectively. The molecular formula of the compound will be
MEDIUM
In a compound C, H and N are present in 9:1:3.5 by weight. If molecular weight of compound is 108, the molecular formula of compound is
HARD
The ratio of mass percent of C and H of an organic compound CXHYOZ is 6 : 1. If one molecule of the above compound CXHYOZ contains half as much oxygen as required to burn one molecule of compound CXHY completely to CO2 and H2O. The empirical formula of the compound CXHYOZ is
MEDIUM
_____ is the symbolic representation of a molecule of a compound.
HARD

Chemical formula of glucose is represented as _____.

(A) C6H12O6                (B) C12H22O11                (C)C5H10O

Enter your correct answer as A, B or C.

EASY
The valency of HCO3- is _____. 1/2
MEDIUM
In the formation of sodium chloride, each chlorine gains _____ electron.
EASY
The valencies of the two elements of a binary compound are _____ to obtain its formula. (added / transposed)
EASY
The empirical formula of Acetylene is _____.