Please help thank you! Which of the following is the correct definition for a compound?

A substance that can be separated into two or more substances only by chemical means.
A substance that cannot be separated into more substances.

A substance that can be separated into two or more substances by chemical or physical means.

A substance that can be separated into two or more substances only by physical means.

A: A substance that can be separated into two or more substances only by chemical means.

Explanation:

The best answer for this would be A. A compound in general is when two or more elements are bonded chemically. That is, the elements are joined in a chemical reaction. An example of a compound is table salt; (sodium chloride) NaCl. It, like all chemicals, can be separated into both of its components, so B is out. The other two answers basically say is it either only chemical or physical means that can separate it, when the answer is that it is only chemical changes that can separate a compound. There can be a reaction when a compound is broken up. You might think that you can separate salt crystals with a hammer or some physical force, but that's only the salt lattice, not the Na and Cl coming apart. Also, for the compound water, H2O, the Hydrogen and Oxygen can be separated by running an electric current through the water sample. This chemically alters the water molecule and splits it up, which is a chemical change. So, to sum up here, you can only use chemical means to separate a compound. Take care!

A: A substance that can be separated into two or more substances only by chemical means.

Explanation:

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

it forms an anion that has a larger radius. anions have a negative charge and are larger than the original atom.