All categories

2 years ago

Which of the following is an example of a physical change?

Chemistry

1 answer:

Pavel [41]2 years ago

3 0

Answer:

A. A solid dissolves.

Explanation:

The physical change from the given choices is that a solid dissolves.

The dissolution of a solute in a solvent is a physical change and not a chemical change.

A physical change has the following properties:

they are easily reversible
leads to the production of no new kinds of matter
involves no change in mass
requires little energy

You might be interested in

If the rock has a mass of 250.8 grams, what is its density?

cluponka [151]

To know the density you also need to know the volume of the rock.

4 0

3 years ago

Experiments were carried out in which a beam of cathode rays was first bent by a magnetic field and then bent back by an electro

Sergio039 [100]

a. the ratio of mass to charge of an electron

Explanation:

The experiment permitted the direct measurement of the ratio of mass to charge of an electron.

The charge to mass ratio of an electron was determine by accelerating a beam of cathode rays in magnetic and electric fields.
No matter the gas used in the tube or the nature of the material of the electrodes, the rays were found to have constant charge to mass ratio of 1.76 x 10¹¹coulombkg⁻¹.

learn more:

Subatomic particles brainly.com/question/2757829

#learnwithBrainly

6 0

3 years ago

Which of the following has the highest pH?

Tema [17]

Answer:

Explanation:

pH=-log(x)

x=0.001M,pH=3

x=0.01M,pH=2

x=0.1M,pH=1

x=1M,pH=0

Highest pH is for option D

7 0

2 years ago

Read 2 more answers

A cleaning bottle contains 83.1 g of ammonia. How many molecules of ammonia are in the bottle?

Tasya [4]

Answer:

2.94 x $10^2^4$

Explanation:

First we need to find out how many moles of ammonia there are, using the formula: Mass = mr x moles.

We know the mass is 83.1g, now we need to find the mR of ammonia - NH3.

N = 14, H = 1, so 14 + (3x1) = an mr of 17.

Moles = mass/ mr = 83.1/17 = 4.8882

Now we can multiply the moles by avogadro's constant to find the number of molecules:

4.8882 x (6.02 x $10^2^3$ ) = 2.94 x $10^2^4$ molecules of ammonia

4 0

3 years ago

What mass of chromium would be produced from the reaction of 57.0 g of potassium with 199 g of chromium(II) bromide according to

fredd [130]

Answer:

Mass of Chromium produced = 37.91 grams

Explanation:

2K + CrBr₂ → 2KBr + Cr

2mole 1 mole 1 mole

mass of Potassium = 57.0 grams

molar mass of Potassium = 39.1 g/mol

no of moles of Potassium = 57.0 / 39.1 = 1.458 moles

mass of CrBr₂= 199 grams

molar mass of CrBr₂ = 211.8 gram/mole

no of moles of CrBr₂ = 199 / 211.8 = 0.939 mole

From chemical equation

1 mole of CrBr₂ = 2 moles of K

∴ 0.939 moles of CrBr₂ = ?

⇒ 0.939 x 2/1 = 1.878 moles of K

1.878 moles of K is needed, but there is 1.458 moles of K. So, Potassium is completed first during the reaction . Hence, Potassium is limiting reagent. and CrBr₂ is excess reagent .

From chemical equation

2 moles of K = 1 mole of Cr

∴ 1.458 moles of K = ?

⇒ 1.458 x 1/ 2 = 0.729 moles of Cr

no of moles of Cr formed = 0.729 moles

molar mass of Cr = 52.0 g/mol

mass of one mole of Cr = 52.0 grams

mass of 0.729 moles of Cr = 52.0 x 0.729 = 37.908 grams

mass of Chromium produced = 37.91 grams

6 0

3 years ago