what type of radiation emits helium ions and can be stopped by a piece of paper

HESI A2

HESI A2 Chemistry Practice Test

1. Which type of radiation emits helium ions and can be stopped by a piece of paper?

A. Beta radiation
B. Alpha radiation
C. Gamma radiation
D. X-ray radiation

Correct answer: B

Rationale: Alpha radiation emits helium ions, which are helium nuclei without electrons, making them positively charged. These ions are relatively large and heavy compared to beta and gamma radiation. Due to their size and charge, alpha particles interact strongly with matter and are easily stopped. A piece of paper or even human skin can effectively block alpha radiation. Therefore, alpha radiation is the type of radiation that can be stopped by a piece of paper. Beta radiation consists of fast-moving electrons and can penetrate further into materials than alpha radiation, thus not stopped by a piece of paper. Gamma radiation is highly penetrating and requires dense materials like lead or concrete to block it effectively. X-ray radiation, similar to gamma radiation, is also highly penetrating and cannot be stopped by a piece of paper.

2. Which of the following is false?

A. Animal cells use lysosomes to break down old cells
B. Animal cells use chloroplasts to gain energy
C. Plant cells have a cell wall to maintain structure
D. All of the above are true

Correct answer: B

Rationale: The statement "B. Animal cells use chloroplasts to gain energy" is false. Chloroplasts are only present in plant cells and certain algae, where they are responsible for photosynthesis to generate energy from sunlight. Animal cells rely on other organelles, such as mitochondria, for energy production. Choice A is true because animal cells use lysosomes to break down old cells and cellular waste. Choice C is true as plant cells have a cell wall composed of cellulose that provides structural support and protection.

3. Which hormone is produced by the adrenal cortex?

A. Insulin
B. Cortisol
C. Thyroxine
D. Glucagon

Correct answer: B

Rationale: The correct answer is B, Cortisol. Cortisol is the hormone produced by the adrenal cortex. It plays a crucial role in regulating metabolism, immune response, and managing stress. Insulin is produced by the pancreas, thyroxine by the thyroid gland, and glucagon by the pancreas. Therefore, choices A, C, and D are incorrect as they are not hormones produced by the adrenal cortex.

4. 15\25 + 42\52 = ?

A. 1 3/10
B. 1 1/10
C. 1\10\2024
D. 3\10\2024

Correct answer: A

Rationale: 15\25 + 42\52 simplifies to 1 3\10.

5. How much paint do you need to paint the interior walls and floor of a rectangular swimming pool with dimensions 8m by 5m and a depth of 2m? (Assume one can of paint covers 10 sq m)

A. 56 sq m
B. 72 sq m
C. 88 sq m
D. 104 sq m

Correct answer: C

Rationale: To calculate the total area to be painted, find the area of each wall and the floor, sum them up, and subtract the area of the top surface of the pool. The area to be painted is (2*8 + 2*5 + 8*5) = 16 + 10 + 40 = 66 sq m. Since one can of paint covers 10 sq m, divide the total area (66 sq m) by the coverage area per can to determine the number of cans needed. Therefore, you need 88 sq m of paint, which is equivalent to 9 cans of paint. Choice A, B, and D are incorrect as they do not represent the correct calculation of the total area to be painted.