1)If a bar of a silver 40 cm long, 25 cm wide and 15 cm deep weighs 157.5 kg, wh

ID: 1071509 • Letter: 1

Question

1)If a bar of a silver 40 cm long, 25 cm wide and 15 cm deep weighs 157.5 kg, what is the density of the silver in g/cm3?

2)A compound contains 28 g of nitrogen and 16 g of oxygen. What is the empirical formula of this compound?

a)NO

b)NO2

c)N2O

d)NO3

e)N28O16

3) Which of the following is a chemical property of magnesium?

a)Mg is a good conductor of both heat and electricity.

b)A freshly cut surface of magnesium quickly loses its luster as it reacts with oxygen in the air to form an ionic compound.

c)Magnesium melts at 649 °C.

d)Both b and c.

e)None of the above.

4) What is the systematic name for CuI2?

a)Copper iodide

b)Copper diiodide

c)Copper (I) iodide

d)Copper (II) iodide

e)Dicopper iodide

1)
mass = 157.5 kg = 157500 g

volume = 40 cm * 25 cm * 15 cm
= 15000 cm^3

density = mass/volume
= 157500 g / 15000 cm^3
= 10.5 g/cm^3

Answer: 10.5 g/cm^3

2)
N : 28 g
O : 16 g
divide each by their molar mass
N : 28/14 = 2
O : 16/16 = 1

empirical formula is N2O

Answer: c

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