Question

Which of the following does not have a uniform composition throughout? A) Compound B) Homogeneous mixture C) Heterogeneous mixture D) Solvent E) Element The mass of a sample is 550 milligrams. Which of the following expresses that mass in kilograms? A) 5.5 times 10^5 kg B) 5.5 times 10^-4 kg C) 5.5 times 10^-1 kg D) 5.5 times 10^8 E) 5.5 times 10^-6 kg What is the volume of a container that contains 14.3 g of a substance having a density of 0.988 g/cm^3? A) 691 cm^3 B) 14.1 cm^3 C) 14.5 cm^3 D) 141 cm^3 E) 0.0691 cm^3 How many neutrons are there in an atom of lead whose mass number is 208? A) 126 B) 82 C) 290 D) 208 E) none of them

Answer 1

Answer:

Explanation:

Heterogeneous mixture = C

1 gram = 1000 milligram

1000gram= 1kg

1000x1000 milligram = 1kg

1,000,000milligram = 1kg

550milligram = 550/1,000,000 = 5.5 x 10 ^ -4

5.5 times 10^-4 kg= B

Density = Mass / Volume

Volume = mass / density = 14.3/0.988 = 14.47cm^3

Lead has 82 protons,

An atom comprises of proton and neutrons.

the number of neutrons in an atom of lead given as 208 will then

Atom = proton + neutron

208 = 82 + neutron

208 -82 = 126 neutrons