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4 years ago

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Chemistry

2 answers:

leonid [27]4 years ago

5 0

Answer:

1 ) A change in color of substance

2) The given statement is false.

3) A burning of candle is a chemical change.

Explanation:

A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.

Example : Melting of ice

Physical property is defined as the property which can be measured and whose value describes the state of physical system. For Example: State, density etc.

A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.

Example: Corrosion of iron called as rusting.

Chemical property is defined as the property of a substance which is observed during a reaction where the chemical composition identity of the substance gets changed.

Precipitate is solid substance formed from the mixing of two different solutions.

Zinaida [17]4 years ago

4 0

1. a change in the color of a substance

2. False, a precipitate is a solid not a gas

3. a burning candle

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The number of electrons (e- ) is

levacccp [35]

Answer:

The number of electrons in a neutral atom is equal to the number of protons. The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus. The number of neutrons is equal to the difference between the mass number of the atom (M) and the atomic number (Z).

Explanation:

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3 years ago

How many moles of sulfur are in 53.7 grams of sulfur?

PolarNik [594]

NO.OF.MOLES= MASS/ATOMIC MASS
THE ATOMICITY OF SULPHUR IS 8 AND ITS MASS NUMBER IS 32.
SO, THE ATOMIC MASS IS 256
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3 years ago

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Which type of wave do the particles in a medium move parallel to the direction that the waves move

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Longitudinal waves. In a longitudinal wave the particles in the medium move parallel to the direction waves go. A good example can be the p-waves in an earthquake.

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4 years ago

2 ways friction is helpful and 2 ways it does not

iris [78.8K]

Benefits of friction.

1. Walking. Friction between the soles of our shoes and the ground enables us to walk. The sole of the shoe is held to the ground through friction. This is what is termed as "grip" of the shoe. The more grip a shoes offers, the better and faster we can walk.

2. Writing. Writing using a pen requires friction. It is impossible to hold a pen in the hand without friction because it would slip out. Also the graphite point of the pencil would not make a mark on the paper without friction.

Drawbacks of friction

1. Drag. An aircraft taking off experiences significant friction between it and the air resulting in drag, so much fuel has to be used to create energy to overcome the wind resistance.

2. Surface hindrance. Friction makes moving something heavy from one part of a room to another very difficult. Sliding a large box across the flour takes a lot of energy due to friction between the box and the floor.

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3 years ago

Match the following. 1. A mixture that does not have a uniform composition and the individual components remain distinct. polar

Ganezh [65]

Answer:

Explanation:

1. A mixture that does not have a uniform composition and the individual components remain distinct.

HETEROGENEOUS

An heterogeous mixture is a mixture with components in different phases.

2. A mixture that does have a uniform composition throughout and is always in the same state.

HOMOGENOUS

Homogenous mixtures have just one phase that is uniform all through.

3. A substance that will not dissolve in a solvent.

INSOLUBLE

When a solute cannot dissolve in a solvent to form a solution, we say it is insoluble.

4. A homogeneous mixture

SOLUTION

Solutions are made up of homogenous mixtures solute and solvent.

5. A molecule with no internal charge variation due to bonding.

NON-POLAR

Even distribution of charges especially between species whose electronegativity difference is 0 would lead to the formation of a non-polar compound. Here,

6. A molecule with an uneven distribution of charge due to unequal sharing of electrons during bonding

POLAR

Unequal sharing of electrons forms a polar compound. The more electronegative attracts the shared electron to itself and there is separation of charges. This leads to polarity.

7. A solution which has dissolved as much solute as it can at a particular temperature.

SATURATED

A saturated solution cannot dissolve more solute beacuse it contains enough solute as it can dissolve at a temperature.

8. A solution which is still able to dissolve solute.

UNSATURATED

An unsaturated solution is able to dissolve more solute.

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3 years ago