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aniked [119]
3 years ago
9

The tip of a match is ignited as it is struck against the matchbox. Why is this a chemical change? a.The color of the match tip

has changed. b.The match changes size as it burns. c.The tip of the match is flammable and is set on fire. d.The match is melting.
Chemistry
2 answers:
Rama09 [41]3 years ago
4 0

Answer:

C

Explanation:

irga5000 [103]3 years ago
3 0

It's (C.: The tip of the match is flammable and is set on fire.

Hope this helps! I got the answer right on my test!

:)

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If the initial [NO2] is 0.260 M, it will take ________ s for the concentration to drop to 0.150 M. If the initial is 0.260 , it
Nitella [24]

The question is incomplete, here is the complete question:

At elevated temperature, nitrogen dioxide decomposes to nitrogen oxide and oxygen gas

NO_2\rightarrow NO+\frac{1}{2}O_2

The reaction is second order for NO_2 with a rate constant of 0.543M^{-1}s^{-1} at 300°C. If the initial [NO₂] is 0.260 M, it will take ________ s for the concentration to drop to 0.150 M

a) 1.01    b) 5.19     c) 0.299      d) 0.0880     e) 3.34

<u>Answer:</u> The time taken is 5.19 seconds

<u>Explanation:</u>

The integrated rate law equation for second order reaction follows:

k=\frac{1}{t}\left (\frac{1}{[A]}-\frac{1}{[A]_o}\right)

where,

k = rate constant = 0.543M^{-1}s^{-1}

t = time taken  = ?

[A] = concentration of substance after time 't' = 0.150 M

[A]_o = Initial concentration = 0.260 M

Putting values in above equation, we get:

0.543=\frac{1}{t}\left (\frac{1}{(0.150)}-\frac{1}{(0.260)}\right)\\\\t=5.19s

Hence, the time taken is 5.19 seconds

6 0
3 years ago
19) The nuclear symbol of helium,
Amiraneli [1.4K]

Answer:

Alpha particle

Explanation:

The helium symbol is also used to represent he alpha particles.

For example:

The americium with atomic wight  224 undergo alpha decay and produce

₉₃Np²³⁷ . The alpha particle emitted is also called helium nuclei. During this decay some gamma radiations also produce as a byproduct.

₉₅Am²²⁴   →    ₉₃Np²³⁷ + ₂He⁴

Properties of alpha radiation:

Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number 4 less than and atomic number 2 less than the starting atom.

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

4 0
3 years ago
What does mechanical digestion mean ?
Alex787 [66]

Answer:

Explanation:

Mechanical digestion involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion. The role of chemical digestion is to further degrade the molecular structure of the ingested compounds by digestive enzymes into a form that is absorbable into the bloodstream.

4 0
3 years ago
The molarity of concentrated acetic acid is 17.45 M. When acetic acid is diluted in water it is commonly called vinegar with a m
Sladkaya [172]

M1 = 17.45 M

M2 = 0.83 M

V2 = 250 ml

M1. V1= M2. V2

V1 = (M2. V2)/M1 = (0.83× 250)/ 17.45= 11.89 ml

7 0
3 years ago
Your lab partner named this compound 3-methyl-4-n-propylhexane, but that is not correct.
loris [4]

<u>Answer:</u> The correct IUPAC name of the alkane is 4-ethyl-3-methylheptane

<u>Explanation:</u>

The IUPAC nomenclature of alkanes are given as follows:

  • Select the longest possible carbon chain.
  • For the number of carbon atom, we add prefix as 'meth' for 1, 'eth' for 2, 'prop' for 3, 'but' for 4, 'pent' for 5, 'hex' for 6, 'sept' for 7, 'oct' for 8, 'nona' for 9 and 'deca' for 10.
  • A suffix '-ane' is added at the end of the name.
  • If two of more similar alkyl groups are present, then the words 'di', 'tri' 'tetra' and so on are used to specify the number of times these alkyl groups appear in the chain.

We are given:

An alkane having chemical name as 3-methyl-4-n-propylhexane. This will not be the correct name of the alkane because the longest possible carbon chain has 7 Carbon atoms, not 6 carbon atoms

The image of the given alkane is shown in the image below.

Hence, the correct IUPAC name of the alkane is 4-ethyl-3-methylheptane

4 0
3 years ago
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