School and Work

the first one : 10x-30=15x-40
10=5x
x=2

the other equations are like this.......

Good luck

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Where can I find the answers? They have answers for the summary questions but not examination style questions. And this is for testing myself and checking my answers for revision and is NOT cheating

YES, I have already asked this question and I am aware I am reposting the exact same thing, this is because some smart ars*s assume that because NOT is in capitals, I must be covering something up, and be cheating in homework.. However if you think logically, when a 17 year old is in their easter holidays and studying for AS levels, the last thing I could possibly care about is homework which is not even set for the majority of my subjects (unless it is to revise, which it mostly is) and I am (like anyone else I know in my whole year) focusing completely on revision and this is achieved one way by testing yourself with a textbook and checking your answers. thank you.

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1. the inference that evolution occurs gradually over time,
a. is not supported by any fossil evidence
b. is known as coevolution
c.is supported by many transiyionl forms in the foaail record
d.was proposed by lyell

4. the traits of individuals best adapted to survive become more common in each new generation because

a. offspring do not inherit those trait
b. the adapatation responsible for those traits increase through natural selection
c. those individuals do not breed
d. natural selection does not affec well adapted individuals

5. natural selection causes
a. changes in the environment
b. plants and animals to produce more offspring than can survive
c. changes in the frequency of certain adapattions in a population
d. genetic variation with populations

6. the similarity in the body shape of a whale an of a fish is an example of
a.divergent evolution
b.convergent evolution
c.coevolution
d.vestigal structures

7. which of the following must exist in a population in order for natural selection to act

a. genetic variation
b. overproduction
c. struggle for survival
d. all of the above

I need it for the practice test study thanks

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Sorry, I could not read the content fromt this page.

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The first thing to understand is what a mole is. It is just a number chemists use to express weight. This many atoms of any element in the periodic table equals its atomic weight. Molecular weight is the sum of atomic weight. Molarity is how chemists express concentration. The units are moles per liter. All weights and volumes in chemistry use the metric system.

The next thing to understand is the definition of pH. It is the negative log of the Hydrogen ion concentration in terms of moles/liter. Both acids each produce a single Hydrogen ion, but their molecular weights are different.

HCl = 1 + 35.5 = 36.5 grams/mole
HNO3 = 1 + 14 + 16*3 = 63 grams/mole

5 grams / (36.5 grams/mole) = 0.137 moles of HCl
5 grams / (63 grams/mole) = 0.079 moles HNO3

0.137 moles / 3.4 liters = 0.040 moles/liter for HCl
0.079 moles / 3.4 liters = 0.023 moles/liter for HNO3

Each mole of acid will produce a mole of Hydrogen ions. This is true for mole fractions as well.

pH of HCl = -LOG(0.040) = 1.39
pH of HNO3 = -LOG(0.023) = 1.63

I would say it was the HCl. The reason the answer was not exact was because the atomic weights were rounded to integers. Try using exact atomic weights and the answer ought to be closer to 1.2.

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