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3 years ago

Please hep its my last question

Chemistry

1 answer:

atroni [7]3 years ago

7 0

Answer:Noble gases:

are highly reactive.

react only with other gases.

do not appear in the periodic table.

are not very reactive with other elements.

Explanation:Noble gases:

are highly reactive.

react only with other gases.

do not appear in the periodic table.

are not very reactive with other elements.

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Could someone please care to explain what the answer is

polet [3.4K]

Calculate the percentage composition of Ca(MnO4)2.

Firstly, we see how many atoms are there for each element in the formula.

Ca= 1 atom

Mn= 2 atoms

O= 8 atoms

Next, we are going to consult our periodic table for the atomic mass of each element.

Ca= 40

Mn= 55

O= 16

Then, we have to find the molar mass for the compound..

Here is the formula for calculating molar mass of an element:

Molar Mass= ( no. of atoms of the element × atomic mass of the element)

Now, we have to calculate the atomic mass of the compound. So using the molar mass formula for an element, we calculate the molar mass for each element then we sum up their molar masses to get the compounds molar mass.

Molar mass (Ca)= 1× 40

(Ca)= 40

Molar mass (Mn)=2×55

(Mn)= 110

Molar mass (O)= 8×16

(O)= 128

Now: Molar mass( compound)= (Ca)+(Mn)+(O)

= 40+ 110 128

= 278

This is everything we need to calculate our percentage composition for each element..

* The example says to find the percentage composition for Ca. So we only find for Ca, Which is already done using the formula and the answer is 14.39%.

To prove that your answer is correct, find the percentage composition for Mn and O as well. Then you add up their percentage compositions.

If you do and you get 100 as your answer, then your percentage compositions are correct.

Why don't you try finding the percentage composition for Mn and O, then add up all the three percentage compositions. If you 100 as their sum, then your percentage composition for each of the elements are correct.

6 0

3 years ago

Maggie is solving a chemistry riddle her clue is to take the number of valence electrons in halogens and subtract it by the numb

Novay_Z [31]

The answer to the riddle Maggie is solving is 6

To determine the answer to the riddle Maggie is solving,

We will subtract the number of valence electrons in halogens by the number of valence electrons in alkali metals.

First, let us define what is meant by valence electrons

Valence electrons are those electrons that reside in the outermost shell surrounding an atomic nucleus.

Now, we will the determine the respective number of valence electrons in halogens as well as the number of valence electrons in alkali metals.

For Halogens

Halogens are the group 17 (group 7A) elements in the periodic table. Examples are Fluorine, Chlorine, Bromine etc.

Halogens have 7 electrons in their outermost shell

For Alkali metals

Alkali metals are the group 1 metals. Examples are Lithium, Sodium, Potassium etc.

Alkali metals have 1 electron in their outermost shell

Now, for the answer to the riddle,

Answer to the riddle = Number of valence electrons in halogens - Number of valence electrons in Alkali metals

Answer to the riddle = 7 - 1

∴ Answer to the riddle = 6

Hence, the answer to the riddle Maggie is solving is 6

Learn more here: brainly.com/question/9392364

6 0

3 years ago

What mineral element present in a bridge

OLga [1]

A mineral found in a bridge is iron

3 0

3 years ago

Given the relative abundance of the following naturally occurring isotopes of oxygen, calculate the average atomic mass of oxyge

STatiana [176]

The average atomic mass of oxygen is 16 amu.

According to the formula of average atomic mass of oxygen

= $\frac{Sum of (Mass of each isotope)(relative abundance)}{100} \\\\= \frac{((16)(99.76)+(17)(0.037)+(18)(0.204)}{100} \\\\=16 amu$

6 0

4 years ago

Read 2 more answers

Carbon-14 is likely to undergo which of the following nuclear decay process, in order to:

Aleks04 [339]

Answer:

a)beta decay; to reduce the number of neutrons

Explanation:

When an isotope decays by beta decay, a neutron is converted into a proton, an electron and a neutrino (a particle that serves to balance spins). This process reduces the neutron/proton ratio.

During the beta decay of carbon-14, an atom of 14C decays into an atom of 14N. Hence the number of protons in the atom increases by one, creating a nitrogen atom.

8 0

4 years ago