Question

Choose the one alternative that best completes the statement or answers the question. 1 kilogram = 1000 milligrams 10,000 1 times 10^-6 1,00,000 1,000 None of the above. Of the objects below. ______ is the most dense. an object with a volume of 139 mL, and a mass of 93 g an object with a volume of 13 cm^3, and a mass of 1.29 times 10^3g an object with a volume of 2.5L, and a mass of 12.5 kg An object with a volume of 3.91 times 10^-24 nm^3 and a mass of 7.93 g times 10^-1 mg An object with a volume of 0.00212 m^3, and a mass of 4.22 times 10^4 mg 1 picometer = ______ centimeters 1 times 10^8 1 times 10^-8 1 times 10^-12 1 times 10^10 1 times 10^-10 Write the word or phrase that best completes each statement or answer the question. 1 milligram = _____ micrograms. A sample of tetrachloroethylene. a liquid used in dry cleaning that is being phased out because of its potential to cause cancer, has a mass of 40.55 g and a volume of 25.0 ml. at 25ml What is its density at this temperature? Will tetra chloroethylene float on water? (Materials that are less dense than water will float.) (b) Carbon dioxide (CO_2) it a gas at room temperature and pressure. However, carbon dioxide can be put under pressure to become a 'supercritical fluid' that is a much safer dry cleaning agent than tetrachloroethylene. At a certain pressure, the density of supercritical CO_2, is 0.469 g/cm^3. What is the mass of a 25.0 ml sample of super critical CO_2 at this pressure? Indicate the number of significant figures in each of the following measured quantities: (a) 3.774 km. (b) 205 m^2, (c) 1.700 cm, (d) 350.00 K, (e) 307.080, (f) 1.3 times 10^3 m/s.

Answer 1

7) 1 Kilogram = 1000000 milligrams

1 Kg = 1000 gm and 1 gm = 1000 mg, hence, 1 Kg = 1000 * 1000 mg = 1000000 mg

8) Density (d) = mass/volume

A. 139ml and 93 g $\therefore$ d = 93/139 = 0.66907 g/ml

B. 13dm³ and 1290 g ; 1dm³ = 1000ml

$\therefore$ d = 1290/13000 = 0.09923 g/ml

C. 2.5L and 12.5 kg; 2.5L = 2500ml; 12.5kg= 12500 g

$\therefore$ d = 12500/2500 = 5 g/ml

D. 3.91*10^-24 nm³ and 7.93*10^-1 ng; 1 nm³ = 1*10^-21 ml $\therefore$ 3.91*10^-24 nm³ = 3.91* 10^-45 ml

and 1ng = 1*10^-9 g; 7.93*10^-1 ng = 7.93*10^-10 g

$\therefore$ d = 7.93*10^-10 g/3.91* 10^-45 ml = 2.02813*10³⁵ g/ml

E. 1m³ = 1000000 ml $\therefore$ 0.00212 m³ = 2120 ml

and 4.22*10⁴ mg = 42.2 g

d= 42.2/ 2120 = 0.01991 g/ml

Hence the highest density is of D. (3.91*10^-24 nm³ and 7.93*10^-1 ng)

9) 1 picometer = 1*10-¹⁰ cm (Answer is E)

10) 1mg = 1000 micrograms

11) Density of TCE = 40.55/25 = 1.622 gm/ml and density of water is 1 gm/ml, hence, densuty of TCE more than water and hence, it will not float on water.

Density of SuperC. CO₂ = 0.469 gm/ml, we know, d = mass/volume $\therefore$ mass = 0.469*25 = 11.725 gm.