1. Which is not an example of a physical change to a wooden stick?

1 answer:

5 0

The answer is C. burning the stick. This is because burning the stick will change the chemical properties of the wood, and it will not be wood anymore, it will be ash and the rest will be heart or gas.

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Which of the following hydrocarbons has a double bond in its carbon skeleton?1) C3H82) C2H63) CH44) C2H45) C2H2

Kipish [7]

Answer:

C₂H₄ (option number 4)

Explanation:

A hydrocarbon with a double bond in its carbon skeleton is an alkene and has the general form:

$C_nH_{2n}$ .

This is, the number of hydrogen atoms is twice the number of carbon atoms.

On the other hand, alkanes have only single bonds, and the compounds with a triple bond in its carbon skeleton are alkynes.

Review each choice:

1) C₃H₈:

In this case, the number of hydrogen atoms is 2×3 + 2 = 6 + 2 = 8, which is corresponds to an alkane, not an alkene.

2) C₂H₆

For this, the number of hydrogen atoms is 2 × 2 + 2 = 4 + 2 = 6. Again an alkane, not alkene.

3) CH₄

Hydrogen atoms: 1 × 2 + 2 = 4 ⇒ an alkane

4) C₂H₄

Hydrogen atoms: 2 × 2 = 4. This is precisely the relation for an alkene, so this is the hydrocarbon that has a double bond in its carbon skeleton.

The chemical formula may be writen as CH₂ = CH₂, to show the double bond.

So, this is the correct answer.

5) C₂H₂

Hydrogen atoms: 2 × 2 - 2 = 4 - 2 = 2. This relation of carbon and hydrogen atoms corresponds to a compound with triple bond, i.e an alkyne: CH≡CH.

8 0

3 years ago

Campare and Conteast Physical and chemical properties.

I am Lyosha [343]

Answer:

Physical properties are changes in color, weight, mass, density, volume, whether it is freezing, tarnishing, boiling, etc. while chemical properties are changes in the compound of the object such as whether an object is/isn't flammable, affected by acid, it dissolves, ferments, rots, ignites in water, etc.

Explanation:

Physical property examples: a piece of steel is cut in half, a sugar cube is ground up into a powder, ice melts into water, clouds form in the sky, you mow the lawn, the water turned purple when you dropped red and blue dye in it, leaves grow in the spring, ethyl alcohol boils at 79° C, you cut apples up

Chemical property examples: pancakes cook on the griddle, fireworks explode in th sky, Alka-Seltzer gives off carbon dioxide when added to water, roasting a marshmellow, milk sours when left on the counter, burning wood in a bonfire, salt dissolves in water, food is digested in the stomach

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3 years ago

The reactants in a chemical reaction contain 900 J of chemical energy. The products of the reaction contain 9000 J of chemical e

Agata [3.3K]

Answer:The reaction absorbs 8100 J of energy from the surroundings as it proceeds.

Explanation:

7 0

2 years ago

Read 2 more answers

Please help. 1.600x10^8 / 8.000x10^11

sweet-ann [11.9K]

Answer: