The density of an object with a volume of 5.0ml and a mass of 20.0g is
15.0g/ml
0.25g/ml
100.0g/ml
4.0g/ml

The density of the object will be 4 g/ml.

Explanation:

Density is defined as the mass contained per unit volume.

Given : Mass of object = 20.0 grams

Volume of object=

Putting in the values we get:

Thus density of the object will be 4 g/ml.

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