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3 years ago

Mendeleev created this table as he noticed that a

Chemistry

1 answer:

Nimfa-mama [501]3 years ago

4 0

Answer:

Mendeleev had left the noble gases out of his periodic table.

Explanation:

Mendeleev's periodic table is pictured in the image attached to the question.

Mendeleev's table obviously lacked the noble gases. The reason for this grave omission is simple; the noble gases were not known as at the time when he formulated his periodic table. There weren't any known elements whose properties were similar to the properties of the noble gases. This would have lead him to suspect their existence.

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What chemical changes happen at school

kykrilka [37]

Burning, cooking

Explanation:

Chemical changes that happens in school are:

Cooking of meals

Burning of wastes

Chemical reactions in laboratories

Rusting of iron used in construction

A chemical change is a change that produces new kinds of substances.
These changes are usually accompanied by energy and mass changes.
Most of such changes are not reversible.

Chemical changes are driven by change in chemical properties of matter.

In a school, iron components might begin to rust. This is a chemical change.

learn more:

Chemical change brainly.com/question/9388643

#learnwithBrainly

8 0

3 years ago

37.9 grams of an unknown substance undergoes a temperature increase of

jenyasd209 [6]

Answer:

1.023 J / g °C

Explanation:

m = 37.9 grams

ΔT = 25.0*C

H = 969 J

c = ?

The equation relating these equation is;

H = mcΔT

making c subject of formulae;

c = H / mΔT

c = 969 J / (37.9 g * 25.0*C)

Upon solving;

c = 1.023 J / g °C

4 0

3 years ago

The Thompson analogy titled "The Carpet-Seed Children Analogy" attempts to deal with the issue of failed ____________________(A)

vazorg [7]

Answer: (D) contraception

Explanation:

8 0

3 years ago

State the basicity of this acid HCOOH

Katena32 [7]

Answer:

The basicity of HCOOH (otherwise known as formic acid) is 1

Explanation:

5 0

3 years ago

One of relatively few reactions that takes place directly between two solids at room temperature is In this equation, the in Ba(

yuradex [85]

Answer:

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate.

Explanation:

$Ba(OH)_2.8H_2O(s)+NH_4SCN(s)\rightarrow Ba(SCN)_2(s)+8H_2O(l)+NH_3(g)$

The balance chemical equation is :

$Ba(OH)_2.8H_2O(s)+2NH_4SCN(s)\rightarrow Ba(SCN)_2(s)+10H_2O(l)+2NH_3(g)$

Mass of barium hydroxide octahydrate = 6.5 g

Moles of barium hydroxide octahydrate = $\frac{6.5 g}{315 g/mol}=0.020635 mol$

According to reaction, 2 moles of ammonium thiocyanate reacts with1 mole of barium hydroxide octahydrate. The 0.020635 moles of barium hydroxide octahydrate will react with:

$\frac{2}{1}\times 0.020635 mol=0.04127 mol$

Mass of 0.04127 moles of ammonium thiocyanate;

$0.04127 mol\times 76 g/mol=3.136 g\approx 3.14 g$

3.14 grams of ammonium thiocyanate must be used to react completely with 6.5 g barium hydroxide octahydrate

3 0

3 years ago