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2 years ago

GIVING BRAINLIEST FOR RIGHT ANSWERS PLS HELP

Chemistry

2 answers:

BigorU [14]2 years ago

5 0

Answer:

: Chemical change; Chemical property of heat of combustion

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 of a substance which becomes evident during physical changes. Example: Melting point

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: combustion

Chemical property is defined as the property of a substance which becomes evident during chemical changes. Example: Reactivity with other substances

Thus when a piece of coal and a piece of wood is burnt , there is formation of new substances and thus is a chemical change. Combustion is a chemical property as it is reactivity of a substance with oxygen.

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Anuta_ua [19.1K]2 years ago

4 0

Answer:

Answer: Chemical change; Chemical property of heat of combustion

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.

Explanation:

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Use the information below to explain why the atomic radius decreases down a group.

notsponge [240]

Answer:

Detail is given below

Explanation:

Atomic radii trend along group:

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.

As the size of atom increases the ionization energy from top to bottom also decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.

In A we can see that there is one positive charge and force of attraction is 2.30×10⁻⁸ N and distance is 0.10 nm

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3 years ago

How many moles of carbon are in 7.87x10^7 carbon molecules?

zaharov [31]

There are 6.022*10^23 molecules in 1 mole of carbon
So how many will moles will be 7.87*20^7?
Let the required number of moles be ‘x’.
1 mole ———6.022*10^23
x moles———7.87*10^7
(Cross multiplication)
x=7.87*10^7/6.022*10^23
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2 years ago

40 POINTS

Llana [10]

Answer:

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mesosphere

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Explanation:

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7 0

2 years ago

You have 500.0 ml of a buffer solution containing 0.30 m acetic acid (ch3cooh) and 0.20 m sodium acetate (ch3coona). what will t

Nataly [62]

First, we should get moles acetic acid = molarity * volume

=0.3 M * 0.5 L

= 0.15 mol

then, we should get moles acetate = molarity * volume

= 0.2 M * 0.5L

= 0.1 mol

then, we have to get moles of OH- which added:

moles OH- = molarity * volume

= 1 M * 0.02L

= 0.02 mol

when the reaction equation is:

CH3COOH + OH- → CH3COO- + H2O

moles acetic acid after adding OH- = (0.15-0.02)

= 0.13M

moles acetate after adding OH- = (0.1 + 0.02)

= 0.12 M

Total volume = 0.5 L + 0.02 L= 0.52 L

∴[acetic acid] = moles acetic acid after adding OH- / total volume

= 0.13mol / 0.52L

= 0.25 M

and [acetate ) = 0.12 mol / 0.52L

= 0.23 M

by using H-H equation we can get PH:

PH = Pka + ㏒[salt/acid]

when we have Ka = 1.8 x 10^-5

∴Pka = -㏒Ka

= -㏒ 1.8 x 10^-5

= 4.7

So by substitution:

∴ PH = 4.7 + ㏒[acetate/acetic acid]

= 4.7 + ㏒(0.23/0.25)

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2 years ago

A solution of a salt of a weak acid HY is added to a solution of another weak acid HX. Based on the information given above, whi

Sloan [31]

Answer: the strongest base will be A) HX(aq)

Explanation:

The cationic part of the base is formed from the cation in the weak acidic salt solution, (say Na2CO3= HY, and H= Na) i.e H+, whereas the anionic part of the base comes from the the weak base ( say NH4OH= HX, and X= OH-)

Then the strong base formed will be HX

8 0

3 years ago