Answer:
for question no. 1 OPTION b is correct
Elements are pure substances made up of molecules
The ozone layer protects humans from harmful UV rays, because it acts as a sort of filter for any toxic or overpowering waves from damaging our skin. This goes for animals, as well.
Answer:
a. alkyne
b. alkane
c. alkyne
d. alkene
Explanation:
The general formula for each class of compound is given below
Alkane: 
Alkene: 
Alkyne:
(assuming single multiple bonds)
Now let us classify according to the above formulas:
a. It has two hydrogen atoms less than the two times of carbon atoms hence, it's alkyne
b. It has two hydrogen atoms more than the two times of carbon atoms hence, it's alkane
c. It has two hydrogen atoms less than the two times of carbon atoms hence, it's alkyne
d. It has hydrogen atoms two times of carbon atoms hence, it's alkene
0.81 moles
Explanation:
cobalt chloride when dissolved in water dissociate into cobalt and chloride ions as shown;
CoCl₂ (s) → [Co²⁺](aq) + 2[Cl⁻] (aq)
The mole ratio between CoCl₂ and [Co²⁺] is 1 ; 1 while the mole ratio between CoCl₂ and [Cl⁻] is 1 : 2
Therefore; 0.27 moles of CoCl₂ will form;
(1 * 0.27) = 0.27 moles of [Co²⁺] ions
(2 * 0.27) = 0.54 moles of [Cl⁻] ions
Total moles of dissociated ions are;
0.27 + 0.54
= 0.81 moles