Heidi is a chocolate lover and eats chocolate daily. She has a bad break-out and her friend told her eating chocolate causes pimples. Heidi continues to eat
chocolate every day for 2 weeks and counts the number of pimples she has on
her face. The following 2 weeks she doesn't eat any chocolate and counts the
number of pimples on her face.
a. Independent Variable =
b. Dependent Variable =
C. Control =

a. the weeks she ate the chocolate

b. how many pimples were on her face

c. how much chocolate she ate

(I'm pretty sure A. is right but I might be wrong)

Explanation:

a. Independent Variable = time , starting number of pimples

b. Dependent Variable = the number of pimples

C. Control =  the chocolate quantity , 2 weeks for eating and 2 weeks for chocolate fasting " The think this time equalizing is a control factor "

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g