Praxis 2 (5435) Exam with Complete Solutions
Which of the following poses the greatest safety risk while being heated in a school laboratory?
(A) A mixture of iron and sulfur
(B) Mercury(II) oxide
(C) Sodium chloride
(D) Copper(II) sulfate hydrate Correct answer-The best answer is (B). Mercury(II) oxide
breaks down on heating to metallic mercury and oxygen. Mercury vapor that is given off is
highly toxic when inhaled or absorbed through the skin, and exposure to mercury in a school
should be greatly limited if not eliminated altogether.
A piece of paper that appears blue in sunlight is illuminated solely by a red light that is passed
through a green filter. What color does the paper appear under this illumination?
(A) Blue (B) Green (C) Red (D) Black Correct answer-The correct answer is (D). The green
filter absorbs all colors except green, which it passes. Therefore, the red light will be absorbed
by the filter, which will pass no light. The paper will not be illuminated, and so it will appear
black, regardless of its initial color.
What quantity of oxygen, O2, contains very nearly the same number of molecules as 36.0 grams
of water, H2O?
(A) 64.0 grams
(B) 32.0 grams
(C) 16.0 grams
(D) 8.0 grams Correct answer-The correct answer is (A). 36 grams of water is 2 moles (2 X
, 18 grams). A 2-mole sample of O2 contains the same number of molecules as does 2 moles of
any other substance. A 2-mole sample of O2 would have a mass of
2 X 32.0 grams = 64.0 grams.
Which of the following is the most reasonable conclusion that can be drawn from the data?
Data - Tall Hybrid - treated - 50cm in 10 days
- water only - 35cm in 10 days
Dwarf Hybrid - treated - 35 cm in 10 days
- water only - 20cm in 10 days
(A) The new fertilizer influences the growth of both corn varieties tested
(B) The new fertilizer causes faster growth rate for both varieties than do other fertilizers
(C) The new fertilizer improves the root system of the tall hybrid to a greater extent than it does
that of the dwarf hybrid
(D) The new fertilizer is effective in producing faster growth for both varieties for the first 10
days only Correct answer-The correct answer is (A). The graphs indicate more rapid
growth for the treated samples than for the untreated samples in both corn varieties. The other
options describe results not tested in the experiments and so not indicated by the data.
A person heterozygous for the recessive gene for cystic fibrosis marries a person who does not
carry or have the trait (homozygous dominant). What is the probability that the couple's first
child will be a carrier?
(A) 0.0 (B) 0.25 (C) 0.50 (D) 1.0 Correct answer-The correct answer is (C). One parent will
have the genotype CC and the other parent will have the genotype Cc. The possible genotypes
Which of the following poses the greatest safety risk while being heated in a school laboratory?
(A) A mixture of iron and sulfur
(B) Mercury(II) oxide
(C) Sodium chloride
(D) Copper(II) sulfate hydrate Correct answer-The best answer is (B). Mercury(II) oxide
breaks down on heating to metallic mercury and oxygen. Mercury vapor that is given off is
highly toxic when inhaled or absorbed through the skin, and exposure to mercury in a school
should be greatly limited if not eliminated altogether.
A piece of paper that appears blue in sunlight is illuminated solely by a red light that is passed
through a green filter. What color does the paper appear under this illumination?
(A) Blue (B) Green (C) Red (D) Black Correct answer-The correct answer is (D). The green
filter absorbs all colors except green, which it passes. Therefore, the red light will be absorbed
by the filter, which will pass no light. The paper will not be illuminated, and so it will appear
black, regardless of its initial color.
What quantity of oxygen, O2, contains very nearly the same number of molecules as 36.0 grams
of water, H2O?
(A) 64.0 grams
(B) 32.0 grams
(C) 16.0 grams
(D) 8.0 grams Correct answer-The correct answer is (A). 36 grams of water is 2 moles (2 X
, 18 grams). A 2-mole sample of O2 contains the same number of molecules as does 2 moles of
any other substance. A 2-mole sample of O2 would have a mass of
2 X 32.0 grams = 64.0 grams.
Which of the following is the most reasonable conclusion that can be drawn from the data?
Data - Tall Hybrid - treated - 50cm in 10 days
- water only - 35cm in 10 days
Dwarf Hybrid - treated - 35 cm in 10 days
- water only - 20cm in 10 days
(A) The new fertilizer influences the growth of both corn varieties tested
(B) The new fertilizer causes faster growth rate for both varieties than do other fertilizers
(C) The new fertilizer improves the root system of the tall hybrid to a greater extent than it does
that of the dwarf hybrid
(D) The new fertilizer is effective in producing faster growth for both varieties for the first 10
days only Correct answer-The correct answer is (A). The graphs indicate more rapid
growth for the treated samples than for the untreated samples in both corn varieties. The other
options describe results not tested in the experiments and so not indicated by the data.
A person heterozygous for the recessive gene for cystic fibrosis marries a person who does not
carry or have the trait (homozygous dominant). What is the probability that the couple's first
child will be a carrier?
(A) 0.0 (B) 0.25 (C) 0.50 (D) 1.0 Correct answer-The correct answer is (C). One parent will
have the genotype CC and the other parent will have the genotype Cc. The possible genotypes
