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Explain the following terms:

(a) flux, (b)gangue,

(c) slag, (d) smelting.

A student puts his signature with graphite pencil. If the mass of carbon in the signature is 10⁻¹² g. Calculate the number of carbon atoms in the signature.

Which of the following reactions does not occur in Bessemer convertor in the extraction of copper from chalcopyrites?

Which element is diamond composed of?

Which term is used to indicate the development of unpleasant smell and taste in fat and oil containing foods due to aerial oxidation (when they are kept exposed for a condiderable time) ?

What is the chemical formula of slaked lime?

Why is bio gas also termed as gobar gas?

Heat is ___ in ___ reaction whereas ___ in ___ reaction.

In a solid, $P$ atoms form $FCC,Q$ atoms are present in alternate edge centres, $R$ in alternate tetrahedral voids. If $P$ atoms on the two face centres are replaced by $X$ atoms, then the formula of the compounds is

Complete the following reaction:
Zn+conc.HNO3→Zn(NO3)2+H2O+

Explain, why (or give reasons for)

(i) In the laboratory preparation of hydrogen chloride from sodium chloride, the gas can be obtained below 200°C or above. But the lower temperature is preferred.

(ii) Hydrogen chloride is not collected over water.

(iii) Hydrochloric acid cannot be concentrated above 22.2% by boiling.

(iv) HCl gas does not conduct electricity, but hydrochloric acid conducts electricity.

(v) Only a very dilute solution of hydrogen chloride in water can be concentrated by boiling the solution while a very concentrated solution would become less concentrated when boiled.

(vi) When the stopper of a bottle full of HCl gas is opened there are fumes in the air.

(vii) A solution of HCl gas in water turns blue litmus red and conducts electricity, while HCl gas dissolves in toluene and it has no effect on litmus and does not conduct electricity.

(viii) An aqueous solution of chlorine is acidic in nature.

From the metals: copper, iron,magnesium, sodium, and zinc, select a different metal in each case which:

(a) does not react with dilute hydrochloric acid,

(b) can form $2^{+}$ and $3^{+}$ ions,

(c) has a hydroxide that reacts with both acids and alkalis,

(d) does not react with cold water but reacts with steam when heated.

(e) Arrange the above metals in their decreasing order of reactivity.

(a) What is the atomic number of carbon? Write its electronic configuration.
(b) What type of chemical bonds are formed by carbon? Why?
(c) Name the three allotropic forms of carbon.

Which of the following pairs of compounds of carbon will undergo combustion as well as addition reactions?

Aju read a fact that bronze contains 88% copper and 12% tin. So, there will be ___ grams of copper in 200 grams of bronze.

Which of the following atoms would qualify as a heteroatom in organic chemistry?

The principle behind froth floatation method involves the difference in the ________of the ore and the gangue particles.

Metal + Acid → ___ + ___

Classify the following compounds as alkanes, alkenes and alkynes. [3 MARKS]

${\text{C}}_5{\text{H}}_{1}2$ , ${\text{C}}_2{\text{H}}_4$, ${\text{C}}_3{\text{H}}_4$, ${\text{C}}_3{\text{H}}_8$, ${\text{C}}_4{\text{H}}_8$, ${\text{C}}_5{\text{H}}_8$

Three alcohols - ethanol, propanol and butanol are mixed and heated for a long time in a beaker. Which is the last one to evaporate?

Explain the role of decomposers in the environment.

Give two tests for hydrochloric acid.