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Snowcat [4.5K]
2 years ago
5

Pure substances contain only one type of a. Atoms only. B. Molecules only. C. Atoms or molecules. D. Mixture.

Chemistry
2 answers:
hammer [34]2 years ago
6 0

Pure substances contain atoms only. You cannot break down a pure substance.  An element is always uniform all the way through. An element CANNOT be separated into simpler materials except during nuclear reactions.

Nesterboy [21]2 years ago
3 0
A. Atoms only. An element cannot be separated into simpler materials
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A student wants to examine a substance by altering the bonds within its molecules. Which of the following properties of the subs
Marrrta [24]

Question is incomplete, the complete question is as follows:

A student wants to examine a substance by altering the bonds within its molecules. Which of the following properties of the substance should the student examine?

A. Toxicity, because it can be observed by altering the state of the substance

B. Boiling point, because it can be observed by altering the state of the substance

C. Toxicity, because it can be observed by replacing the atoms of the substance with new atoms

D. Boiling point, because it can be observed by replacing the atoms of the substance with new atoms

Answer:

B.

Explanation:

A student can examine a substance without altering the bonds within the molecules by examining its boiling point.

The boiling point is the property of a substance, at which the substance changes its state, which is from solid to liquid, liquid to gas and others. So, examining the boiling point will alter the bonds within the molecules as the state of substance will change.

Hence, the correct answer is "B".

6 0
3 years ago
The Periodic Table of the Elements organizes elements according to their properties. A section of the periodic table is shown. W
horrorfan [7]
You haven't attached any options but anyways, to help you with your question, elements belonging to the same group (e.g. alkali metals, noble gases) all have the same chemical properties. Hydrogen, for example, have the same properties with Sodium, Potassium and Lithium.
3 0
3 years ago
Selenium (Se) has 30 protons and 20 neutrons in each atom, therefore its atomic
allochka39001 [22]

Answer:

30, 50

Explanation:

Hello,

In this since an element's atomic number is equal to the number of protons in its atom, we can infer that selenium's atomic number is 30. Moreover, due to the fact the the neutrons are equal to the atomic mass minus the atomic number or the number of protons, by knowing the number of neutrons we compute the atomic as follows:

neutrons=mass-protons\\\\mass=neutrons+protons\\\\mass=30+20\\\\mass=50a.m.u

Thus, answer is 30, 50.

Best regards.

8 0
3 years ago
Sodium tert-butoxide (NaOC(CH3)3) is classified as bulky and acts as Bronsted Lowry base in the reaction. It is reacted with 2-c
IceJOKER [234]

Answer:but-1-ene

Explanation:This is an E2 elimination reaction .

Kindly refer the attachment for complete reaction and products.

Sodium tert-butoxide is a bulky base and hence cannot approach the substrate 2-chlorobutane from the more substituted end and hence major product formed here would not be following zaitsev rule of elimination reaction.

Sodium tert-butoxide would approach from the less hindered side that is through the primary centre and hence would lead to the formation of 1-butene .The major product formed in this reaction would be 1-butene .

As the mechanism of the reaction is E-2 so it will be a concerted mechanism and as sodium tert-butoxide will start abstracting the primary hydrogen through the less hindered side simultaneously chlorine will start leaving. As the steric repulsion in this case is less hence the transition state is relatively stabilised and leads to the formation of a kinetic product 1-butene.

Kinetic product are formed when reactions are dependent upon rate and not on thermodynamical stability.

2-butene is more thermodynamically6 stable as compared to 1-butene  

The major product formed does not follow the zaitsev rule of forming a more substituted alkene as sodium tert-butoxide cannot approach to abstract the secondary proton due to steric hindrance.

5 0
3 years ago
What is the complete ionic equation for H2SO4(aq) + Cal2(aq) -> CaSO4(s) + 2HI(aq)?
eimsori [14]
2H(+) + SO4(2-) + Ca(2+) + 2I(-) -> CaSO4(s) + 2H(+) + 2I(-)
The signs in brackets are the subscripts for the charge of the ion. This is the complete ionic equation. The net ionic equation is:
Ca(2+) + SO4(2-) -> CaSO4
6 0
2 years ago
Read 2 more answers
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