Can someone help me with the answers to some of my questions( I have the answer to some of the them) I need help with questions 4,5,9,19, 21,and 23)


4.A science class is conducting experiments to demonstrate conservation of mass. Both lab groups, A and B, use the same type of candle and burn them for the same amount of time. Which statement most accurately summarizes the expected results of the experiment?

Hint to Answer:Since A is a closed system, the law of conservation of matter will be followed. Since B is an open system, it could be difficult to account for all of the reactants and products.


5. 5. What type of chemical reaction is this?

4 Al + 3 O2 --> 2 Al2O3

A. single replacement

B.synthesis

C.double replacement

D. combustion


9.Match the half-life information to each correct answer.

Remember to use the table below or use your fingers like we did in class.

*Oxygen-22 has a half life of 2.25 seconds. How long would it take a 64 gram sample to decay into a 32 gram sample?

answer:✅2.25 seconds

*There are 24 grams of Rhodium-101 in a sample. Rhodium-101 has a half life of 3.3 years. How many grams of Rhodium-101 will remain after 6.6 years?

*Sodium-24 has a half life of 15 hours. What fraction of the sample is still Sodium-24 after 45 hours?

*Mercury-210 has a half life of 10 minutes. How many grams of a 200 gram sample remain after 40 minutes?


answer choices: 1/8, 12.5 g, 6 g,


21.Aiden climbs an apple tree and drops apples down to his classmate Aidan who is standing on the ground. The apples have an average mass of 0.080 kg. Which statement is false?


23.A student is asked to determine whether a wave is sound or light by playing 20 questions with their partner.

Which question would not help them to determine whether the wave is light or sound?

A. Does the wave transfer energy or matter?

B. Does the wave vibrate air molecules in the same direction as the wave transfers energy?

C. Does the wave travel faster in gases, liquids, or solids?