Explanation:
The first involves keeping the surface of the concrete moist by the use ponding, spraying/sprinkling, damp sand or damp hessian.
The second prevents the loss of moisture from the concrete by covering it with polythene sheeting or leaving the formwork in place.
The third involves the use of spray or roller applied curing compounds.
Answer:
b. independent/manipulated variable
Explanation:
Independent/manipulated variable - refers to the variable that is changed by the scientist or an experimenter. Only one variable that is independent is required to ensure a fair test in an excellent experiment. As the independent variable is being changed by an experimenter or scientist, data is being recorded simultaneously as they are collected.
The mass of iron (III) oxide (Fe2O3) : 85.12 g
<h3>Further explanation</h3>
Given
3.20x10²³ formula units
Required
The mass
Solution
1 mole = 6.02.10²³ particles
Can be formulated :
N = n x No
N = number of particles
n = mol
No = 6.02.10²³ = Avogadro's number
mol of Fe₂O₃ :
mass of Fe₂O₃ (MW=160 g/mol)
The projectile is the bullet it's self. the chemicals create the explosion to project the bullet