Question

Q19. Read the passage and answer any four questions: The simplest compounds, which are made up of two different elements are called binary

(1844)

compounds. While writing the chemical formulae for compounds, the constituent elements and their valencies are written. Then crossover the valencies of the combining atoms. For the ionic compound, the symbol of cation written first followed by the symbol of the anion. Then their charges are crisscrossed to get the formula. The positive and negative charges must balance each other and the overall structure should be neutral. The molecular mass of a

substance is the sum of atomic masses of all the atoms in a molecule of the substance. (At mass of Ca=40u, H=lu, O=164, N=14u, Cl=35.5u)

i.

Which of the following statements correctly justifies that crystallization technique considered better than simple evaporation to purify solid?

a. Solid decompose or get charred on heating to dryness

b. Impurities may remain dissolved in the solution even after

c. Both (a) and (b)

d. Impurities are easily removed in solution

In magnesium chloride,

a. One

b. Two

c. Three d. Four

The molecular mass of HNO, is

a. 63u b. 7u

c. 54u d. 45u

The formula unit mass of CaCl, is

a. 1lu

b. 342u

C. 213 u

d. 122u

The formula unit mass of a substance is:

a. The sum of atomic masses of all atoms b. The sum of atomic mass of only one atom

C. Both (a) and (b) d. None of these

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Answer 1

Answer:

records and traces of online activities of users are called carbon trail. (true). (false)