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3 years ago

Define a physical change and give one example

Chemistry

1 answer:

ladessa [460]3 years ago

7 0

Answer:

The definition of a physical change is: A physical change is a type of change in which the form of matter is altered but one substance is not transformed into another. The size or shape of matter may be changed but no chemical reactions occur.

An example of physical change is: crumbling a piece of paper or freezing water into ice.

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PLEASE HURRY!!!

bekas [8.4K]

Answer:

high ph -basic,low pH -acidic

Explanation:

hi I'm from India nice to meet you

5 0

2 years ago

Q2. 0.254 g of KHP (204 g/mol) titrated against 20.0 mL of unknown NaOH (40.0 g/mol) solution to get the end point of phenolpht

Vera_Pavlovna [14]

Answer:

Mass concentration (g/L) = 2.49g/L.

Explanation:

No. of moles = $\frac{mass}{molar mass}$

= $\frac{0.254}{204}$ = 0.001245 moles

Concentration of KHP (C1) in litres = n/v

= $\frac{0.001245}{0.02}$ = 0.062 mol/L

We know that:

$C_{1} V_{1}$ = $C_{2} V_{2}$

where c1v1 and c2v2 are the products of concentration and volumes of KHP and NaOH respectively.

Since mole ratio is 1 : 1.

1 mole of NaOH - 40g

0.001245 mole of NaOH = 40 × 0.001245 = 0.0498g

⇒0.0498g of NaOH was used during the titration

∴Mass concentration (g/L) = 0.0498g ÷ 0.02L

= 2.49g/L.

3 0

3 years ago

Proteins contain a. oxygen b. nitrogen c. hydrogen

seraphim [82]

Answer:

All of the above

Explanation:

Proteins contain a long chain of amino acids which are a chain of oxygen, nitrogen, carbon, hydrogen or sulfur.

HOPE THIS HELPED

7 0

2 years ago

Read 2 more answers

Purchasing the correctly sized BMX bike is based on the height of the rider. In order to fit a customer, the salesman can use th

Phantasy [73]

Answer: Your best answer is A.

Explanation: 1.35 is a constant and thus is does not change. The equation can be simplified to-
“b = (0.29 x h)+ 1.35”
So, if your rider is say 60 inches tall, the equation would change to-
“b = (0.29 x 60)+ 1.35”
Then to-
“b = (17.4) + 1.35” or “b = 17.4 + 1.35”
And therefore the size of the BMX bike frame in inches would be-
“b = 18.75”

Hope this helped :)

5 0

1 year ago

To what temperature does a 250 ml cylinder containing 0.40 grams of helium gas need to be collected in order for the pressure to

VMariaS [17]

Answer:

T =76.13 K

Explanation:

Given data:

Temperature of gas = ?

Volume of gas = 250 mL(250/1000 = 0.25 L)

Mass of helium = 0.40 g

Pressure of gas = 253.25 kpa (253.25/101 = 2.5 atm)

Solution:

Formula:

PV = nRT

First of all we will determine the number of moles of helium.

Number of moles = mass/ molar mass

Number of moles = 0.40 g/ 4 g/mol

Number of moles = 0.1 mol

Now we will put the values.

R = general gas constant = 0.0821 atm.L/ mol.K

T = PV/nR

T =2.5 atm× 0.25 L /0.1 mol ×0.0821 atm.L/ mol.K

T = 0.625 /0.00821/K

T =76.13 K

6 0

3 years ago