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dezoksy [38]
2 years ago
8

For which of the following activities might you want to hire a chemist?

Chemistry
2 answers:
worty [1.4K]2 years ago
7 0

For which of the following activities might you want to hire a chemist?

Answer: D. testing a rock sample for gold content

Which of the following procedures involves a physical change in one of the substances?

Answer: C. separating a salt solution by evaporating the water

Crank2 years ago
6 0

A. examining the structure of plant cells  

Incorrect. A biologist is required.  

B. building a fence

Incorrect. A carpenter is required.  

C. building a wood storage shed

Incorrect. A carpenter is required.  

D. testing a rock sample for gold content

Incorrect. A chemist is required.  

A. creating salt by reacting sodium metal and chlorine gas

Incorrect. This is a chemical change as a new product is formed.  

B. allowing a nail rust

Incorrect. This is a chemical change as it is the oxidation of iron to form iron oxide, rust.  

C. separating a salt solution by evaporating the water

Correct. This is a physical change as salt gets separated from water and no new product is formed.  

D. building a model rocket propelled by mixing baking soda and vinegar

Incorrect. This is a chemical change.  

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2. A sample of neon gas has a volume of 87.6 L at STP. How many moles are present?
PSYCHO15rus [73]

Answer:

                      3.91 moles of Neon

Explanation:

According to Avogadro's Law, same volume of any gas at standard temperature (273.15 K or O °C) and pressure (1 atm) will occupy same volume. And one mole of any Ideal gas occupies 22.4 dm³ (1 dm³ = 1 L).

Data Given:

                 n = moles = <u>???</u>

                 V = Volume = 87.6 L

Solution:

               As 22.4 L volume is occupied by one mole of gas then the 16.8 L of this gas will contain....

                          = ( 1 mole × 87.6 L) ÷ 22.4 L

                          = 3.91 moles

<h3>2nd Method:</h3>

                     Assuming that the gas is acting ideally, hence, applying ideal gas equation.

                              P V  =  n R T      ∴  R  =  0.08205 L⋅atm⋅K⁻¹⋅mol⁻¹

Solving for n,

                              n  =  P V / R T

Putting values,

                              n  =  (1 atm × 87.6 L)/(0.08205 L⋅atm⋅K⁻¹⋅mol⁻¹ × 273.15K)

                              n  =  3.91 moles

Result:

          87.6 L of Neon gas will contain 3.91 moles at standard temperature and pressure.

7 0
2 years ago
What is the wavelength of light that has a frequency of 3.7 x 1014 Hz? Show all work!!!
kramer

Answer:

Explanation:

f=\frac{c}{\lambda}=>\lambda=\frac{c}{f}=\frac{300x10^8\frac{m}{s}}{3.7*10^{14}\frac{1}{s}}=810.8108*10^{-9}m

3 0
2 years ago
Read 2 more answers
What is the mass percentage of silicon?​
Mkey [24]

Answer: 46.743%

Explanation: what is the mass percentage of silicon?​ 46.743%

***If you found my answer helpful, please give me the brainliest, please give a nice rating, and the thanks ( heart icon :) ***

8 0
2 years ago
Please help :) ill mark you as the brainiest hope you have a good day
Hitman42 [59]

Have a wonderful day :) thanks for the points

5 0
3 years ago
which two quantities are used to predict gravitational force according to Newton's law of universal gravitation a. mass and spee
NISA [10]

Answer:

(b). Mass and distance.

Explanation:

The gravitational force between two objects is given by Newton's law of universal gravitation. The formula is as follows :

F=G\dfrac{m_1m_2}{r^2}

Here,

G is universal gravitational constant

r is the distance between two objects

It is very clear that the gravitational force is directly proportional to the product of masses and inversely proportional to the square of the distance between them.

Hence, the two quantities are used to predict gravitational force according to Newton's law of universal gravitation are mass and distance.

7 0
3 years ago
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