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3 years ago

A study of the spectrum of the sun led to the discovery of helium. True False

Chemistry

2 answers:

elixir [45]3 years ago

8 0

Answer:

True

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Explanation:

max2010maxim [7]3 years ago

3 0

Answer:

True

Explanation:

A study of the spectrum of the sun led to the discovery of helium.

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A sample of an uranium compound is found to be losing mass gradually. Explain what is happening to the sample.

yan [13]

Answer:

The uranium in the sample of the compound is radioactive

Explanation:

Some atoms can split on their own. Some split when bombarded by energetic particles. Such atoms are said to be radioactive.

Radioactivity is borne out of the drive of an atom to reach stabillity. Every atom have a specific neutron/proton ratio which ensures stability of the nucleus. A nucleus with a stability ratio different from that which makes it stable will become unstable and split into one or more other nuclei with emissons of energetic particles.

Note: neutrons and protons dictates the mass of an atom. They are located in the nucleus which is the site for nuclear radioactive reactions.

4 0

3 years ago

Which intermolecular force is characteristic of compounds which are liquids at room temperature and have relatively high boiling

SIZIF [17.4K]

Thew answer is hydrogen bonds.

6 0

3 years ago

13. A gas occupies 4.31 liters at a pressure of 0.755 atm. Determine the volume if the

wariber [46]

Answer:

13. 2.60 L.

14. 2.40 L.

Explanation:

We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

R is the general gas constant,

T is the temperature of the gas in K.

If n and T are constant, and have different values of P and V:

(P₁V₁) = (P₂V₂)

13. A gas occupies 4.31 liters at a pressure of 0.755 atm. Determine the volume if the pressure is increased to 1.25 atm.

P₁ = 0.755 atm, V₁ = 4.31 L.

P₂= 1.25 atm, V₂ = ??? L.

∴ V₂ = (P₁V₁)/(P₂) = (0.755 atm)(4.31 L)/(1.25 atm) = 2.60 L.

14. 600.0 mL of a gas is at a pressure of 8.00 atm. What is the volume of the gas at 2.00 at m.

P₁ = 8.0 atm, V₁ = 600.0 mL.

P₂= 2.0 atm, V₂ = ??? L.

∴ V₂ = (P₁V₁)/(P₂) = (8.0 atm)(600.0 mL)/(2.0 atm) = 2400/0 mL = 2.40 L.

3 0

3 years ago

Draw the Lewis structure for BCl3. How many single bonds, double bonds, triple bonds, and unshared pairs of electrons are on the

andreev551 [17]

Answer : The number of single bonds, double bonds, triple bonds, and unshared pairs of electrons on the central atom are, 3, 0, 0 and 0 respectively.

Explanation :

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is, $BCl_3$

As we know that boron has '3' valence electrons and chlorine has '7' valence electrons.

Therefore, the total number of valence electrons in $BCl_3$ = 3 + 3(7) = 24

According to Lewis-dot structure, there are 6 number of bonding electrons and 18 number of non-bonding electrons.

From the Lewis-dot structure we conclude that,

The number of single bonds, double bonds, triple bonds, and unshared pairs of electrons on the central atom are, 3, 0, 0 and 0 respectively.

3 0

4 years ago

How many molecules of fructose would you have if you have 0.7 moles of fructose? *

iogann1982 [59]

Answer:

4.214 × 10^23 molecules.

Explanation:

Number of molecules in a substance can be calculated by multiplying the number of moles in that substance by Avagadro's number, which is 6.02 × 10^23.

That is, no. of molecule = n × Avagadro constant

In this case, there are 0.7 moles of fructose. Hence;

number of molecules = 0.7 × 6.02 × 10^23

no. of molecule = 4.214 × 10^23 molecules.

5 0

3 years ago