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Over [174]
3 years ago
14

Please help me please

Chemistry
2 answers:
AnnZ [28]3 years ago
8 0

Answer:

20 is b and 21 is a.

Ludmilka [50]3 years ago
7 0

Answer:

b

Explanation:

i read this once and remember,trust me!

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What is kinetic energy of a 155 kg object moving at speed of 20 m/s
Novay_Z [31]

Answer:

KE = 1/2*m*v^2

KE = 1/2*150kg*(20 m/s)^2

KE = 75kg * 400m²/s²

KE = 30,000 kg*m²/s²

KE = 30,000 N*m

KE = 30,000 J

Explanation:

Hope this helped.

A brainliest is always appreciated.

4 0
2 years ago
When a compound such as X2Z4 is created, what would be the<br> correct simplified chemical formula?
Shtirlitz [24]

Answer:

XZ2

Explanation:

There are different ways in which compounds can be represented. Broadly, we have three different types of formula;

- Structural formular: This shows how th atoms in te compound are connected to each other.

- Molecular formular: This shows the actual number of atoms of element present in the compound

- Empirical Formular: This is the simplest formular of a compound. It basically shows the number of atoms in simple ration to each other.

This question requires us to input the empirical formular;

X2Z4

The ratio of the elements is; 2 : 4 which can be simplified into 1 : 2

This means the empirical formular is XZ2

6 0
3 years ago
The density of solid Cr is 7.15 g/cm3. How many atoms are present per cubic centimeter of Cr?
Masja [62]
To calculate the number of atoms of Cr, we first find the number of moles per unit of cubic centimeter of Cr. Then, use avogadros number for the number of atoms. Calculations are as follows:

1 cm^3 (7.15 g/cm^3) (1 mol / 51.996 g Cr) = 0.14 mol Cr

0.14 mol Cr ( 6.022 x 10^23 atoms Cr / 1 mol Cr ) = 8.28 x 10^22 atoms Cr
8 0
3 years ago
The molar solubility of pbi2 is 1.5 103 m.
Vsevolod [243]

Answer: -

Concentration of PbI₂ = 1.5 x 10⁻³ M

PbI₂ dissociates in water as

PbI₂ ⇄ Pb²⁺ + 2 I⁻

So PbI₂ releases two times the amount of I⁻ as it's own concentration when saturated.

Thus the molar concentration of iodide ion in a saturated PbI₂ solution = [ I⁻] =

= 1.5 x 10⁻³ x 2 M

= 3 x 10⁻³ M

PbI₂ releases the same amount of Pb²⁺ as it's own concentration when saturated.

[Pb²⁺] = 1.5 x 10⁻³ M

So solubility product for PbI₂

Ksp = [Pb²⁺] x [ I⁻]²

=1.5 x 10⁻³ x (3 x 10⁻³)²

= 4.5 x 10⁻⁹

8 0
3 years ago
Describe the trend in electronegativity of the elements ?​
dalvyx [7]

Answer:

On the periodic table, electronegativity generally increases as you move from left to right across a period and decreases as you move down a group. As a result, the most electronegative elements are found on the top right of the periodic table, while the least electronegative elements are found on the bottom left.

Explanation:

Make sure to edit so you don't get copy-writed.

4 0
3 years ago
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