Which of the following is an example of a compounds? Select one:
a. Cu
b. CaCl2
c. Na
d. Nd

b.CaCl2

Explanation:

A compound is  a substance resulting when two or more elements  are are chemically bonded together either ionically or covalently in a fixed ratio.

From the given options we can see that the only compound there  is CaCl2 which is an ionic compound in the fixed  ratio of one calcium ion to two chloride ions.

Other options , Cu,Na and Nd are merely pure substance---Elements

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