CHEMISTRY HIGH SCHOOL

The percentage by mass of Br in the compoundAlBr3 is closest to
(1) 10.% (3) 75%
(2) 25% (4) 90.%

Answers

Answer 1
Answer:

Answer: The correct answer is option(4).

Explanation:

Molar mass of the aluminium bromide, AlBr_3=266.69 g/mol

Atomic mass of bromine = 79.90 g/mol

Percentage of Mass of bromine in AlBr_3:

\% Br\text{ by mass}=\frac{\text{Atomic mass of Br}* \text{Number of Br atoms}* 100}{\text{Molar mass of }AlBr_3}

\% Br\text{ by mass}=(79.90 g/mol* 3* 100)/(266.69 g/mol)=89.97\%\approx 90\%

Hence, the correct answer is option(4).
Answer 2
Answer: What you have to do it find the percentage / solve it. Divide the mass by the entire mass. 
239.7 ÷ 266.68 = 0.898 × 100 = 90% Br.

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Which of these statements is true? A.
Some molecules may contain no atoms.


B.
Some elements found in nature exist as molecules.


C.
Some compounds include only one type of element.


D.
Some atoms are made of two or more different elements. Which of these statements is true?


A.
Some molecules may contain no atoms.


B.
Some elements found in nature exist as molecules.


C.
Some compounds include only one type of element.


D.
Some atoms are made of two or more different elements.

Answers

Pretty sure it's B. If not, then it's C.

The first person to develop the periodic table was _____. Mendeleev Dalton Bohr Rutherford

Answers

Mendeleev was the first.

Answer:

Mendeleev was the first to develop the periodic table

Explanation:

What form of energy provides power for a gas stove?A.nuclear energy
B.electrical energy
C.chemical energy
D.sound energy

Can you explain the answer for me ?

Answers

C . chemical energy will be the answer. In a gas stove, LPG is stored and it is brought out and it reacts with oxygen to give out heat energy. all the other options are not convincing and hence chemical energy is the best answer. 

The tempertaure at which the pressure of the vapor of a liquid is equal to the external pressure acting on the surface of the liquid?

Answers

Answer: Boiling point

Explanation:

Boiling point is the temperature where the vapor pressure of a liquid equals the pressure of the gas present above it.

The normal boiling point of a liquid is the temperature at which its vapor pressure is equal to one atmosphere.

Boiling point depends on the intermolecular forces present between the molecules. More are the intermolecular forces, lesser will be the vapor pressure and thus more heat will be supplied to make vapor pressure equal to the atmospheric pressure. Thus higher will be the boiling point.

Normal boiling point for water is 100^0C.

What is the [H+] of an HCl solution if the pH is measured to be 6? Select one: a. 1 X 10-7 M b. 1 X 10-6 M c. 6 X 10-6 M d. 8 X 10-1 M

Answers

Answer : The correct option is, 1* 10^(-6)M

Explanation :  Given,

The value of pH of HCl = 6

As we know that,

pH : It is defined as the negative logarithm of hydrogen ion or hydronium ion concentration.

The formula of pH is :

pH=-\log [H^+]

Now put all the given values in this formula, we get the concentration of hydrogen ion.

6=-\log [H^+]

[H^+]=1* 10^(-6)M

Therefore, the concentration of hydrogen ion is, 1* 10^(-6)M
pH=-\log_(10) [H^+] \Rightarrow [H^+]=10^(-pH) \n \npH=6 \n\ [H^+]=10^(-6)=1 * 10^(-6)

The answer is B. 1 × 10⁻⁶ M.

What are the thin fibers of the human nervous system that send messages between different parts of the body?A.
nerves





B.
brain





C.
spinal cord





D.
eye

Answers

Answer:

The correct answer is option A, that is, nerves.

Explanation:

The nerves are also known as neurons that make up the nervous system. The nerves are considered as the unique cells, which conduct messages from one section of the body to another, as minute electrical signals. These messages are also called nerve impulses. There are three distinct kinds of neurons known, and each one exhibit a somewhat different function. These are relay neurons, sensory neurons, and motor neurons.
A. Nerves, it's literally the only one that makes sense
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