All categories

4 years ago

Which of the following is an irreversible physical change?

Chemistry

1 answer:

Yuliya22 [10]4 years ago

3 0

Answer:

b) sharpening a pencil

Explanation:

If you melt lead, boil water, or dissolve sugar in water, you can return all of them back to their original state. If you sharpen a pencil, you can't reattach the shavings as they were originally.

You might be interested in

1. Which of the following correctly represents a balance chemical equation? (a) NaCl + 2H2O → 2NaOH + 2Cl2 + H2 (b) 2NaCl+H2O →

butalik [34]

Answer:

thx sa points

Explanation:

8 0

2 years ago

A dolphin travels a distance 20 miles up the coastline in 153 minutes.If 1 mile is equal to 1609 meters,then what is the dolphin

Afina-wow [57]

Answer:

The dolphins average speed is 3.51 $\frac{meters}{seconds}$

Explanation:

First of all, the following rules of three should be applied:

If 1 mile is equal to 1609 meters, 20 miles are equal to how many meters?

$distance=\frac{20 miles*1609 meters}{1 mile}$

distance=32,180 meters

If 1 minute is equal to 60 seconds, 153 minutes is equal to how many seconds?

$time=\frac{153 minutes*60 seconds}{1 minute}$

time= 9,180 seconds

Speed is a physical quantity that expresses the relationship between the space traveled by an object and the time used for it. That is, speed implies the change of position of an object in space within a certain amount of time and is calculated as:

$speed=\frac{distance}{time}$

So in this case the velocity is calculated as:

$speed=\frac{32,180 meters}{9,180 seconds}$

Solving, you get:

Speed= 3.51 $\frac{meters}{seconds}$

The dolphins average speed is 3.51 $\frac{meters}{seconds}$

4 0

3 years ago

Explain, in terms of charge distribution, why a molecule of carbon tetrachloride is a nonpolar molecule.

Pie

Answer:

Explanation:

The covalent bond is the chemical bond between atoms where electrons are shared, forming a molecule. Covalent bonds are established between non-metallic elements, such as hydrogen H, oxygen O and chlorine Cl. These elements have many electrons in their outermost level (valence electrons) and have a tendency to gain electrons to acquire the stability of the electronic structure of noble gas.

The covalent bond between two atoms can be polar or nonpolar. If the atoms are equal, the bond will be nonpolar (since no atom attracts electrons more strongly). But, if the atoms are different, the bond will be polarized towards the most electronegative atom, because it will be the atom that attracts the electron pair with more force. Then it will be polar.

It can occur in a molecule that the bonds are polar and the molecule is nonpolar. This occurs because of the geometry of the molecule, which causes them to cancel the different equal polar bonds of the molecule.

In carbon tetrachloride the bonds are polar, but the tetrahedral geometry of the molecule causes all four dipoles to cancel out and the molecule to be apolar.

6 0

3 years ago

Please help !!!

stiv31 [10]

Answer:

2KClO3 》》2KCl +3O2

C+ O2》》CO2

number of C moles

Required O2 moles (According to the mole ratio )

Relevant to the first equation, find the moles the KClO3, which is used to produce that amount of O2 moles

Now you can find the mass of KClO3

I mentioned the useful steps which can guide you to get the answer.

Explanation:

5 0

3 years ago

Describe what you can do to reduce non-point source water pollution. List at least 3 specific actions, or, write 3 sentences abo

vovangra [49]

Grass planting, laying of straw , putting up sediment fenced or knee high black fabric fences can help reduce no point source water pollution

4 0

3 years ago