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Oduvanchick [21]
3 years ago
12

For her science project, Paula wants to determine if the growth of bacteria in standing rainwater changes over time. She collect

s rainwater and distributes it evenly in 6 jars and places them all indoors in a spot that does not receive a lot of sunlight to limit evaporation. Using a bacteria testing kit, she measures the bacteria in the water in the first jar on the 5th day, second jar on the 7th day, third jar on the 9th day, fourth jar on the 14th day, fifth jar on the 20th day, and sixth jar on the 24th day. What is the independent or manipulated variable in Paula's experiment?
Chemistry
1 answer:
tamaranim1 [39]3 years ago
8 0

Answer:

The correct answer is - the number of days the rainwater stands in the jars.

Explanation:

The independent variable or the manipulating variable is a variable in a research or study is the variable which affects the dependent variable or the variable that is going to measure in the study.

In the study, variables that recieves the treatment and changed in every subject are independent variables and in this study number of days the rainwater standing in various jars that might affect the growth of the bacteria in rainwater.

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An oxide of P contains 50% by mass of P. Its Relative molecular mass is 64. The molecular formula of the oxide is (P=32; O=16)
anygoal [31]

Answer:

B) PO2

Explanation:

first solve empirical formula

50%of P and 50%of O

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P. O

50/32. 50/16

1.5. 3.0

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1.5/1.5. 3.0/1.5

1. :. 2

Empirical formula=PO2

Molecular formula=PO2

(PO2)n= 64

(32+(16×2)=64

(32+32)n=64

64n=64

n= 1

5 0
3 years ago
What are possible reasons for a percent yield that is under 100%
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Answer:

              Percentage Yield is given as,

                 %age Yield  =  Actual Yield / Theoretical Yield × 100

This shows that the %age yield is directly depending upon the actual yield. And most of the time the percentage yield is less than 100 % because of the following factors.

Impure Starting Materials:

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Incomplete Reactions:

                                     Not all reactions go to completion. In many reactions the starting material after some time stops forming the product due to different conditions. Some reactions attain equilibrium and stop increasing the amount of product. While, in some reactions a by products (like water) formed often react with the product to give a reverse reactions. Hence, the chemistry of reactions also causes the decrease in %age yield.

Handling:

               Another major reason for decrease in yield is handling the product. Always some of the product is lost during the workup of the reaction like, taking TLC, doing solvent extraction, doing column chromatography, taking characterization spectrums. So, we can conclude that the %age yield will always be less than 100%.

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<u>Beta decay occurs when, in an unstable nucleus with too many protons or too many neutrons, one of the protons or neutrons transforms into the other.</u> In beta minus decay, a neutron is broken down into a proton, an electron, and an antineutrino (the neutrino antiparticle, meaning it has an opposite charge to the neutrino). In beta decay plus, a prototype breaks down into a neutron, a positron and a neutrino.

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