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3 years ago

In a chemical formula, what is used to indicate the number of atoms of each element?

1 answer:

6 0

The coefficients next to the symbols of entities indicate the number of moles of a substance produced or used in the chemical reaction.

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Calculate the area of a 3.0 inch by 5.0 inch index card in square millimeters (mm). (You can look up the formula for the area of

meriva

Answer:

The area of the given rectangular index card = 9677.4 mm²

Explanation:

Area is defined as the space occupied by a two dimensional shape or object. The SI unit of area is square metre (m²).

The area of a rectangle (A) = length (l) × width (w)

Given dimensions of the rectangle: Length (l) = 5.0 inch, Width (w) = 3.0 inch

Since, 1 inch = 25.4 millimetres (mm)

Therefore, l = 5 × 25.4 = 127 mm, and w = 3 × 25.4 = 76.2 mm

Therefore, the area of the given rectangular index card = A= l × w = 127 mm × 76.2 mm = 9677.4 mm²

5 0

3 years ago

Salt in crude oil must be removed before the oil undergoes processing in a refinery. The

irina1246 [14]

Answer:

$\large \boxed{0.64 \, \%}$

Explanation:

Assume you are using 1 L of water.

Then you are washing 4 L of salty oil.

1. Calculate the mass of the salty oil

Assume the oil has a density of 0.86 g/mL.

$\text{Mass of oil} = \text{4000 mL} \times \dfrac{\text{0.86 g}}{\text{1 mL}} = \text{3440 g}$

2. Calculate the mass of salt in the salty oil

$\text{Mass of salt} = \text{3440 g} \times \dfrac{\text{5 g salt}}{\text{100 g oil}} = \text{172 g salt}$

3. Calculate the mass of salt in the spent water

$\text{Mass of salt} = \text{1000 g water} \times \dfrac{\text{15 g salt}}{\text{100 g water}} = \text{150 g salt}$

4. Mass of salt remaining in washed oil

Mass = 172 g - 150 g = 22 g

5. Concentration of salt in washed oil

$\text{Concentration} = \dfrac{\text{22 g}}{\text{3440 g}} \times 100 \, \% = \mathbf{0.64 \, \%}\\\\\text{The concentration of salt in the washed oil is $\large \boxed{\mathbf{0.64 \, \%}}$}$

3 0

3 years ago

In stars, hydrogen nuclei combine with each other to form helium and other heavier elements. what is this process called?

slega [8]

Hello!

The process in which hydrogen nuclei combine with each other to form helium and other heavier elements is called Nuclear Fusion.

Nuclear Fusion happens when the repulsion between the two nuclei is overcome by the Strong Interaction Force, spending and releasing high amounts of energy.

The two nuclei need to be close enough for Nuclear Fusion to happen, and the energy needed to achieve that is given by the extremely hot temperatures that exist within stars (about 15 000 000 Kelvin). That's why this kind of reactions are common in stars.

Have a nice day!

6 0

3 years ago

DNA is packaged into these compact units

Wittaler [7]

Explanation:

Chromosomal DNA is packaged inside microscopic nuclei with the help of histones. These are positively-charged proteins that strongly adhere to negatively-charged DNA and form complexes called nucleosomes. Each nuclesome is composed of DNA wound 1.65 times around eight histone proteins.

4 0

3 years ago

Read 2 more answers

What property of gases confirms that the space between the particles of gas is significantly larger than when the same substance

leva [86]

The answer is D. Compressibility

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3 years ago