A bar of soap is 12 cm long, 6 cm wide, and 10 cm long. It has a mass of 415 grams. What is the density of the bar of soap?

The scientific theory of _________ states that populations change over time in response to changes in the environment.

Leto [7]

Natural selection I think

5 0

3 years ago

When 20 ml of 0.1 M HCl is mixed with 20

Bas_tet [7]

Answer:

it is b i took the test

Explanation:

4 0

1 year ago

When your grandparents were growing up, they ate

Kryger [21]

It is fresher because of new transportation techniques and refrigerated trailers.

5 0

3 years ago

A compound is 7.74% hydrogen and 92.26% carbon by mass. At 100°C a 0.6883 g sample of the gas occupies 250 mL when the pressure

ycow [4]

Answer: The molecular formula for the compound is $C_6H_6$

Explanation:

We are given:

Percentage of C = 92.26 %

Percentage of H = 7.74 %

Let the mass of compound be 100 g. So, percentages given are taken as mass.

Mass of C = 92.26 g

Mass of H = 7.74 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{92.26g}{12g/mole}=7.68moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{7.74g}{1g/mole}=7.74moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 7.68 moles.

For Carbon = $\frac{7.68}{7.68}=1$

For Hydrogen = $\frac{7.74}{7.68}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H = 1 : 1

The empirical formula for the given compound is $CH$

Calculating the molar mass of the compound:

To calculate the molecular mass, we use the equation given by ideal gas equation:

PV = nRT

Or,

$PV=\frac{m}{M}RT$

where,

P = pressure of the gas = 820 torr

V = Volume of gas = 250 mL = 0.250 L (Conversion factor: 1 L = 1000 mL )

m = mass of gas = 0.6883 g

M = Molar mass of gas = ?

R = Gas constant = $62.3637\text{ L. torr }mol^{-1}K^{-1}$

T = temperature of the gas = $100^oC=(100+273)K=373K$

Putting values in above equation, we get:

$820torr\times 0.250L=\frac{0.6883g}{M}\times 62.3637\text{ L torr }mol^{-1}K^{-1}\times 373K\\\\M=\frac{0.6883\times 62.3637\times 373}{820\times 0.250}=78.10g/mol$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{Molecular mass}}{\text{Empirical mass}}$

We are given:

Mass of molecular formula = 78.10 g/mol

Mass of empirical formula = 13 g/mol

Putting values in above equation, we get:

$n=\frac{78.10g/mol}{13g/mol}=6$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 6)}H_{(1\times 6)}=C_6H_6$

Hence, the molecular formula for the compound is $C_6H_6$

8 0

3 years ago

Record your evidence about the Moon's appearance

Vilka [71]

Answer:

A solar eclipse .

It is one that occurs when the moon gets between the Earth and the Sun and it casts its shadow over the Earth. A solar eclipse only happens during the phase of new moon when the moon is indirect blockage of sun rays from reaching the earth thus causing a full shadow of the moon to fall on the Earth’s surface.

2 A lunar eclipse can only occur when there is a full moon. An eclipse of the moon happens only at full moon and only when the moon passes through some portion of the Earth’s shadow. The shadow in made of a two cone-shaped components, one which is nested inside the other.

3. Earth blocks sunlight from reaching the moon's surface. There are three categories of lunar eclipse according to the blockage of the sun rays. In a penumbral lunar eclipse, the moon passes through Earth’s penumbral shadow. The partial lunar eclipse occurs when a portion of the moon passes through Earth’s umbral shadow. The total lunar eclipse happens when the entire moon passes through Earth’s umbral shadow.

4.When an object in space comes between the sun and earth. It is one that occurs when the moon gets between the Earth and the Sun and it casts its shadow over the Earth. A solar eclipse only happens during the phase of new moon when the moon is indirect blockage of sun rays from reaching the earth thus causing a full shadow of the moon to fall on the Earth’s surface.

5.A total lunar eclipse. In this type of lunar eclipse, the events are clearly visible and striking to view because the Moon surface appear red in color. During the occurrence of the lunar eclipse events, 35% of the entire eclipse is total eclipse.

6. Wide, dark areas and strange spots and ridges –Galileo described the surface of the moon as being uneven and rough. In addition to that, he described the surface as crowded with depressions and bulges. In his original sketches, the long shadows cast by craters were represented by dark sided of the moon sketch.

7. Waxing gibbous .During the cycle of the moon, it undergoes several phases; new moon-new crescent-first quarter-waxing gibbous-full moon-waning gibbous-last quarter-old crescent-new moon. The new moon phase cannot be seen because the part receiving sun rays in then pointed away from the earth. The rest of the phases are visible from the earth.

8. New moon .

During the cycle of the moon, it undergoes several phases; new moon-new crescent-first quarter-waxing gibbous-full moon-waning gibbous-last quarter-old crescent-new moon. The new moon phase cannot be seen because the part receiving sun rays in then pointed away from the earth. The rest of the phases are visible from the earth.

9. Because the Southern Hemisphere has more direct sunlight .During the winter months, the Northern Hemisphere is tilted away from the sun, thus it receive sunrays at an angle thus it experiences the cold weather. At this period, it is summer in the Southern Hemisphere.

Explanation:

4 0

3 years ago