Step-by-step explanation:
Zn + 2HCl => ZnCl2 + H2
Moles of Zn = 13g / (65.38g/mol) = 0.198mol
Volume of HCl = 0.396mol / (0.25mol/dm³) = 1.58dm³.
Volume of H2 = 0.198mol * (22.4dm³/mol) = 4.43dm³.
Factorizing an expression involves writing the expression in simpler forms
The values of z are
or 
The equation is given as:

Expand the equation

Factorize the expression:

Factor out z - 4

Split
or 
Solve for z
or 
Hence, the values of z are
or 
Read more about factorization at:
brainly.com/question/11579257
To square a number means to multiply it by itself. So 9 squared would be:
9x9
Which is
81
I hope this Helps!
The one under the one you picked but im not 100% sure