An equal arm balance is balanced when 20 washers are

An equal-arm balance is balanced when 20 washers are on one side and 10 bolts
are on the other. Four bolts are added to one side. How many washers must be
added to the other side o maintain balance?
a. 14
b. 8
c. 4
d. 2
Correct Ans - B: Since the equal-arm balance is balanced at a ration of 20 washers
to 10 bolts, the weight of the bolts must be double that of the washers. Two washers
are equivalent in mass to 1 bolt. Thus, 4 bolts are equivalent in mass to 8 washers.

An increase of 4 bolts on one side will require 8 washers on the other side to
maintain the balance.
Compounds with different molecular structures but but the same formula are called?
A student wanted to test the effects of different sugars on the growth of a certain
mold. The sugars to be tested were glucose, fructose, and sucrose. One gram of
each sugar was placed in a tube of 10 mL of water, and a bit of the mold was put in
each of the three solutions. To add a control to the experiment, the student should
also have?
Vinegar is a common antidote for the ingestion of lye. What is the chemical process
underlying this treatment?
Undisturbed layers of rock were examined. Mammal, fish, and bird fossils were
found only in the upper layers. Fish were in layers beneath those, and neither fish,
birds, nor mammals were in the deepest layers. This would tend to support the
hypothesis that?
a. vertebrates always coexisted with invertebrates
b. fish were the first vertebrates to evolve
c. all vertebrates evolved at about the same time
d. birds evolved before fish
Correct Ans - B: New layers of sediment cover old ones and provide a record of
emergence of flora and fauna. the fish were the only fossils found in the layers
beneath the upper layers, indicating that they evolved first.