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Vadim26 [7]
3 years ago
15

What causes the seasonal changes viewed in the night sky?

Chemistry
2 answers:
jonny [76]3 years ago
8 0

Answer:

If you look at the night sky different

times of the year you see different

constellation.This change due to the

motion of the earth in it's orbit around

the sun.The shift of the sky is really

the motion of the earth around the sun.

Explanation:

Hope it helps

Ksenya-84 [330]3 years ago
8 0

Explanation:

the factors which bring about the chemical reaction

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Which of the following solutions would have the most basic pH? Assume that they are all 0.10 M in acid at 25C. The acid is follo
pychu [463]

Answer:

Explanation:

Given:

Ka of HClO2 = 1.1 × 10-2

Ka of HCHO2 = 1.8 × 10-4

Ka of HCN = 4.9 × 10-10

Ka of HNO2 = 4.6 × 10-4

Ka of HF = 3.5 × 10-4

All at a concentration of 0.1 M

A.

HA --> H+ + A-

Ka = [H+] × [A-]/[HA]

[H+] = [A-] = x

[HClO2] = 0.1 M

HClO2 --> ClO2^- + H+

1.1 × 10-2 = x^2/0.1

x = sqrt(1.1 × 10^-3

= 0.033 M

pH = -log[H+]

= 1.48

B.

HA --> H+ + A-

Ka = [H+] × [A-]/[HA]

[H+] = [A-] = x

[HCHO2] = 0.1 M

HCHO2 --> CHO2^- + H+

1.8 × 10-4 = x^2/0.1

x = sqrt(1.8 × 10^-5)

= 0.0042 M

pH = -log[H+]

= 2.37

C.

HA --> H+ + A-

Ka = [H+] × [A-]/[HA]

[H+] = [A-] = x

[HCN] = 0.1 M

HCN --> CN- + H+

4.9 × 10-10 = x^2/0.1

x = sqrt(4.9 × 10-11)

= 0.000007 M

pH = -log[H+]

= 5.16

D.

HA --> H+ + A-

Ka = [H+] × [A-]/[HA]

[H+] = [A-] = x

[HNO2] = 0.1 M

HNO2 --> NO2^- + H+

4.6 × 10-4 = x^2/0.1

x = sqrt(4.6 × 10-5)

= 0.0068 M

pH = -log[H+]

= 2.17

E.

HA --> H+ + A-

Ka = [H+] × [A-]/[HA]

[H+] = [A-] = x

[HF] = 0.1 M

HF --> F- + H+

3.5 × 10-4 = x^2/0.1

x = sqrt(3.5 × 10-5)

= 0.0059 M

pH = -log[H+]

= 2.23

a) pH = 1.48

b) pH = 2.37

c) pH = 5.16

d) pH = 2.17

e) pH = 2.33

HCN is most basic because;

smallest Ka

Highest pH value = 5.16

5 0
3 years ago
What is true of an aqueous solution that is 15.0 percent HNO3 by mass?
djverab [1.8K]

Answer:

B. It contains 15.0 grams of HNO₃ per 100 grams of solution.

Explanation:

  • The percent of a solute in a solution is the mass of the solute (g) per 100 g of solution.

<em>So, an aqueous solution that is 15.0 percent HNO₃ by mass means that It contains 15.0 grams of HNO₃ per 100 grams of solution.</em>

6 0
4 years ago
Read 2 more answers
How many elements are in this chemical formula? <br> 2(NH4)2SO4
sesenic [268]

Answer: 30

Explanation:

Sulfur         S  1  

Oxygen         O  4  

Nitrogen N         2  

Hydrogen H         8

15 in total. For 2 moles, 15*2 = 30

6 0
3 years ago
What is the density of object C? Does it sink or float in water?
nirvana33 [79]

Answer:

0.96 g/cm3, and it will float!

Explanation:

I've explained how to do this before (remember me? lol), but ig I'll do it again..

By looking at the graph you can see that Object C has a mass of ~24 grams and a volume of ~25 cm3

Density = Mass/Volume -> 24 grams/25 cm3 = 0.96 g/cm3

Density of water is 1 g/cm3

Object C is less dense than water and therefore will float (just barely, though)

:)

8 0
3 years ago
Read 2 more answers
Elements with similar chemical properties are organized in the same
Ksju [112]
C it is c the answer is c it’s c
6 0
4 years ago
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