All categories

2 years ago

How are physical and chemical changes similar?

2 answers:

8 0

Physical changes occur when substances undergo a change that does not change their chemical composition. It doesnot includes change in chemical composition.
Chemical change is the change that causes the formation of new chemical substance.
A.Neither can change the number of atoms of each element that are present, is the correct answer.

mr Goodwill [35]2 years ago

7 0

I believe the correct response is the first option.

You might be interested in

What type of cloud is highest in the sky?

Jobisdone [24]

Cirrus

I hope that's help

3 0

2 years ago

The starting pressure of a 15°C system was 1.50 atm. If the pressure rose to 1216 torr, what is the new temperature in Celsius?

andrey2020 [161]

Answer:

The new temperature is 34.21 °C

Explanation:

Step 1: Data given

Temperature of the system = 15°C

Pressure at 15°C is 1.50 atm

The pressure rose to 1216 torr (=1216/760 = 1.6 atm)

Step 2: Calculate the new temperature

P1/T1 = P2/T2

⇒ with P1 = the initial pressure = 1.50 atm

⇒ with T1 = the initial temperature = 15°C = 288.15 K

⇒ with P2 = the initial pressure = 1.60 atm

⇒ with T2 = the initial temperature = TO BE DETERMINED

T2 = T1 * (P2 / P1)

T2 = 288.15 * (1.60/1.50)

T2 = 307.36 K = 34.21 °C

The new temperature is 34.21 °C

8 0

2 years ago

[H+] = 2.5 x 10-10 M What’s the pH

Reika [66]

Answer:

9.6

Explanation:

$pH = - log[2.5*10^{-10}]= 9.6$

6 0

3 years ago

A model used for the yield Y of an agricultural crop as a function of the nitrogen level N in the soil (measured in appropriate

lisov135 [29]

Answer:

It is 3.

Explanation:

The model written correctly is:

$Y=\frac{kN}{9+N^2}$

This is a mathematical question, instead of a chemistry question, and you should use calculus to find the nitrogen level that gives the best yield, since this is an optimization problem.

The best yield is the maximum yield, and the maximum, provided that it exists, is found using the first derivative and making it equal to zero: Y' = 0

To find Y' you must use the quotient rule.

$Y'=\frac{(kN)'(9+N^2)- (kN)(9+N^2)'}{(9+N^2)^2}\\ \\Y'=\frac{k(9+N^2)-kN(2N)}{(9+N^2)^2}\\ \\Y'=\frac{9k + kN^2 - 2kN^2}{(9 + N^2)^2}=\frac{9k-kN^2}{(9+N^2)^2}$

Now make Y' = 0

The denominator is never equal to zero, because it is always positive and greater than 9.

Make the numerator equal to zero:

9k - kN² = 0

Factor: k (9 - N²) = 0

Since k is a positve constant, it is not equal to zero, and the other factor, 9 - N², must be equal to zero:

9 - N² = 0 ⇒ (3 - N) (3 + N) = 0

⇒ 3 - N = 0 or 3 + N = 0 ⇒ N = 3 or N = -3.

Since N is nitrogen level, it cannot be negative and the only valid answer is N = 3.

You can prove that it is a maximum (instead of a minimum) finding the second derivative or testing some points around 3 (e.g. 2.5 and 3.5).

8 0

2 years ago

Select the correct answer from each drop-down menu. An atom has 9 electrons and 9 protons at the start. If it loses 2 electrons,

aalyn [17]

Answer:

If it loses to electrons the net charge will be +2. If the atom instead gains 4 electrons, the net charge will be -4.

Explanation: When an atom loses electrons( which are negatively charged), it turns into a cation. This means since there is more protons(which are positively charged) than electrons, the charge is positive. The charge is positive and than the number of electrons lost. It is the exact opposite for gaining electrons.

3 0

2 years ago