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sergeinik [125]
2 years ago
13

2)A relatively unreactive metal that is yellow colored.

Chemistry
1 answer:
Vlad1618 [11]2 years ago
3 0

I think we're in the same class lol

1. Sodium

2. Gold

3.  Helium

4. Sulfur

5. Magnesium

6. Cesium.

7. Silicon

8. fluorine

9. Nickel

10. Magnesium

11. Tungsten

12. hydrogen

13. Calcium

I did my best, here's my answers. Enjoy.

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Please help... will give brainiest
Dvinal [7]

Answer:

The answer will be :

In year 1869

Russian scientist named Dmitri Mendeleev

Chart called Mendeeleves periodic table

increasing atomic masses

physical and chemical properties.

Hope this Helps

Best of luck !!

7 0
3 years ago
Nitrogen and water react to form nitrogen monoxide and hydrogen, like this: N2(g) + 2H2O(g) → 2NO(g) +2H2(g) Also, a chemist fin
Thepotemich [5.8K]

Answer:

Kc for this reaction is 0.43

Explanation:

This is the equilibrium:

N₂(g) + 2H₂O(g) → 2NO(g) +2H₂(g)

And we have all the concentration at equilibrium:

N₂: 0.25M

H₂ : 1.3M

NO: 0.33M

H₂: 1.2M

They are ok, because they are in MOLARITY. (mol/L)

Let's make the expression for Kc

Kc = ( [NO]² . [H₂]² ) / ([N₂] . [H₂O]²)

Kc = (0.33² . 1.2²) / (0.25 . 1.2²)

Kc = 0.4356

In two significant digits. 0.43

8 0
3 years ago
The half-life of cesium-137 is 30 years. suppose we have a 200-mg sample.
Assoli18 [71]
a) To find  the mass after t years:

we will use this formula:

A = Ao / 2^n 

when A =the amount remaining

and Ao = the initial amount

and n = t / t(1/2)

by substitution:

∴ A = 200 mg/ 2^(t/30y)


b) Mass after 90 y :

by  using the previous formula and substitute t by 90 y

A = 200mg/ 2^(90y/30y)

∴ A = 25 mg

C) Time for 1 mg remaining:

when A= Ao/ 2^(t/t(1/2)

so, by substitution:

1 mg = 200 mg / 2^(t/30y)

∴2^(t/30y) = 200 mg  by solving for t

∴ t = 229 y 


7 0
4 years ago
What mass of salt is needed to prepare 600 mL of a 4g/L solution?
OLga [1]
THE ALTERNATIVE IS 4.8g alternative c
5 0
3 years ago
Select the pair that consists of a base and its conjugate acid in that order. CO32−/CO22−
lana [24]

Answer: The pair that consists of a base and its conjugate acid in that order.NH_3/NH_4^+

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.

H_3PO_4\rightarrow H_PO_4{2^-}+2H^+

H_2CO_3\rightarrow HCO_3^-+H^+

NH_3+H^+\rightarrow NH_4^+

HCO_3^-\rightarrow CO_3^{2-}+H^+

NH_3  is gaining a proton, thus it is considered as a brønsted-lowry base and after gaining a proton, it formsNH_4^+  which is a conjugate acid.

3 0
3 years ago
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