how many moles of water are produced when 05 moles of methane ch4 react with excess oxygen

ATI TEAS 7

TEAS 7 science practice questions

1. How many moles of water are produced when 0.5 moles of methane (CH4) react with excess oxygen?

A. 0.5 moles
B. 1 mole
C. 2 moles
D. 3 moles

Correct answer: B

Rationale: The balanced chemical equation for the combustion of methane is: CH4 + 2O2 -> CO2 + 2H2O. This equation shows that 1 mole of methane produces 2 moles of water. Therefore, when 0.5 moles of methane react, they will produce 1 mole of water. The ratio of water to methane is 2:1, meaning that for every mole of methane that reacts, it produces 2 moles of water. Since only 0.5 moles of methane are reacting, the amount of water produced will be half of what would be produced if 1 mole of methane reacted, resulting in 1 mole of water being produced. Choice A is incorrect because it does not consider the stoichiometry of the reaction. Choices C and D are incorrect as they do not align with the balanced chemical equation and the stoichiometric ratios involved in the reaction.

2. As a car accelerates from rest, what happens to its kinetic energy and the work done on it?

A. Both kinetic energy and work done increase.
B. Kinetic energy increases, but work done remains constant.
C. Work done increases, but kinetic energy remains constant.
D. Both kinetic energy and work done remain constant.

Correct answer: A

Rationale: When a car accelerates from rest, its speed and kinetic energy increase. The work done on the car is what increases its kinetic energy, so both kinetic energy and work done increase simultaneously. Option A is correct because acceleration results in an increase in both kinetic energy and the work done on the car. Option B is incorrect because work done is required to increase kinetic energy during acceleration. Option C is incorrect as work done is directly related to the change in kinetic energy. Option D is incorrect as both kinetic energy and work done increase when the car accelerates.

3. Which of the following is NOT a property of a catalyst?

A. Increases the rate of a reaction
B. Remains unchanged after the reaction
C. Lowers the activation energy
D. Creates new products

Correct answer: D

Rationale: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process. It remains unchanged after the reaction, which eliminates option B. A catalyst works by lowering the activation energy required for the reaction to occur, which eliminates option C. A catalyst does not create new products in a reaction; it only facilitates the conversion of reactants into products more efficiently. Therefore, option D is NOT a property of a catalyst.

4. What is the name of the structure that packages DNA in eukaryotic cells?

A. Nucleosome
B. Chromatin
C. Histone
D. Centromere

Correct answer: A

Rationale: - A nucleosome is the basic structural unit of DNA packaging in eukaryotic cells. It consists of DNA wrapped around a core of histone proteins. - Chromatin refers to the complex of DNA and proteins found in the nucleus of a eukaryotic cell, including nucleosomes. - Histones are the proteins around which DNA is wrapped to form nucleosomes. - Centromere is a region of a chromosome where the two sister chromatids are joined and to which spindle fibers attach during cell division.

5. What type of bond connects sugar and phosphate in DNA?

A. Hydrogen
B. Ionic
C. Covalent
D. Overt

Correct answer: C

Rationale: The correct answer is Covalent (C). In DNA, a covalent bond connects sugar and phosphate molecules. This bond involves the sharing of electron pairs between the atoms, providing stability to the DNA structure. Hydrogen bonds are important in DNA structure but are not the primary bond connecting sugar and phosphate. Ionic bonds involve the transfer of electrons, and 'overt' is not a term related to the bond connecting sugar and phosphate in DNA.