Question

1. tomas was studying solutions. he noticed that when he dissolved a solid in water, the amount of water appeared to remain the same. from his observations, he hypothesized that the mass of a solution is equal to the mass of the solvent. then he made three solutions, measuring the mass of the solid and water used for each solution. then he measured the mass of the solution. his results are shown below.

effect of dissolving solids on mass of solutions
solid mass of solid (g) mass of water (g) mass of solution (g)
salt 12 100 112
sugar 11 100 111
baking soda 14 100 114
tomass data do not support his hypothesis. which question should he investigate next?
a. is the volume of a solution equal to the volume of its solvent?
b. is the mass of a solution affected by the type of solvent used?
c. is the amount of solution affected by the type of solute used?
d. is the mass of a solution affected by the temperature of the solvent?

1. in the mid - 1700s, john needham hypothesized that air contained a life force that allowed bacteria to occur by spontaneous generation and spoiled foods. he boiled broth to kill any organisms in the broth and then allowed it to cool. when the soup spoiled, needham concluded that his hypothesis was supported, and that microbes occurred by spontaneous generation from the life force in the air. but louis pasteur disagreed with needhams conclusion. he knew that air contains bacteria. which of pasteurs experiments did needhams hypothesis influence?

a. pasteur showed that rabies can be treated by vaccination.
b. pasteur showed that a silkworm disease was caused by a parasite.
c. pasteur showed that bacteria do not grow by spontaneous generation.
d. pasteur showed that heating can prevent bacteria from spoiling wine and milk.

Explanation:

1. Thomas was studying the mass of solutions with different solutes. His data didn't support his initial hypothesis about mass relationships. To further his research, he should investigate if the mass of a solution is affected by the type of solute used, as this directly relates to his previous work on solutes and solution - mass.
2. Needham hypothesized that microbes occurred by spontaneous generation from a life - force in the air. Pasteur disagreed and his experiments aimed to disprove spontaneous generation. His demonstration that bacteria do not grow by spontaneous generation was directly related to challenging Needham's hypothesis.

Answer:

1. B. Is the mass of a solution affected by the type of solute used?
2. D. Pasteur showed that bacteria do not grow by spontaneous generation.