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Option C is correct : Calcium and magnesium are alkaline earth metals.

Explanation:

From the given option C is correct.

Calcium and magnesium are alkaline earth metals. Both are present in group 2. Each have 2 valence electrons.

All other options are incorrect, because:

a) Chlorine and iodine are alkali metals.

Chlorine and iodine are not alkali metals. These are halogens. Both have seven valence electrons and form salt with alkali metals.

B) Potassium and phosphorus are in the same group.

Potassium and phosphorus are not present in same groups. Potassium is present in group 1 and phosphorus is present in group 15.

d) Boron and silicon are present in same period.

Boron and silicon are not present in same period. Boron is present in period 2 while silicon is present in period 3.

e) Lead and tin both are non metals.

This option is also incorrect because lead and tin both are metals.

Thus, only option C is correct.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml