Chem 3a exam 1

Perform each calculation to the correct number of sig figs. (1.7 x 10^6/2.63x10^5)+7.33

(66) 13.68 = 14

Decide if each calculation has the correct number of sig figs. (908.4-3.4)/3.52x10^4=0.026

905/3.52x10^4=0.0257 so wrong

Decide if each calculation has the correct number of sig figs. (1206.7-0.904)x89=1.07x10^5

= 1205.8x89=1.1 x 10^5 so wrong

What is the difference between a hypothesis and a theory?

A hypothesis is an attempt to explain phenomena. It is a proposal, a guess used to understand and/or predict something. A theory is the result of testing and developing an explanation that is assumed to be true about something. A theory replaces the hypothesis after testing confirms the hypothesis.

What is the difference between a law and a theory?

A law is an observation; a theory is the explanation of that observation. A theory requires experimentation under various conditions. A law has no such experiments. A theory may become obsolete with time. This is not the case with a law. A theory can be replaces by another better theory; however, this never happens with law. A theory may be strong or weak according to the amount of evidence available. A law is a universally observable fact.

Observation, law, or theory? Matter is made of atoms.

A law which is part of Dalton's atomic theory.

Observation, law, or theory? A body in motion stays in motion unless acted upon by a force.

It is a law with slight modification of newtons first law.

Observation, law, or theory? When a metal is burned in a closed container, the sum of the masses of the container and its contents do not change.

It is an observation based on law of conservation of mass.

Observation, law, or theory? The star closest to Earth is moving away from earth at high speed.

It is an observation based on the Doppler effect.

Observation, law, or theory? Matter is conserved in chemical reactions.

Law

Observation, law, or theory? When wood is burned in a closed container, its mass does not change.

Law bases on Lavosier's law of conservation of mass.

A student measures the volume of a gas sample at several different temperatures. The results are tabulated as follows. Formulate a tentative law from measurements.

The ratios indicate that volume to temperature for each measurement is constant which is otherwise called as charles law

1.0yd^2=

ft^2

1.0ft^2=

in^2

Observation, law, or theory? The universe began as a cosmic explosion called the Big Bang.

it is an advanced theory which is widely accepted.

Observation, law, or theory? The stone dropped from an altitude of 450 m falls to the ground in 9.6s.

observation based on newtons laws on motion and gravity

is there 2 sig figs? 24 days

two so true

1.0m^2=

yd^2

Perform each calculation to the correct number of sig figs. 0.004+0.09879

0.10279 so 0.103

Perform each calculation to the correct number of sig figs. (5.01x10^5)/(7.8x10^2)

0.64x10

Perform each calculation to the correct number of sig figs. 89.3 x 77.0 x 0.08

6x10^2

Perform each conversion within the metric system. 4.88fs to picoseconds

72

Perform each calculation to the correct number of sig figs. 1459.3+9.77+4.32

1482.4

Perform each conversion within the metric system. 155.5cm to m

1c, = 10^-2 1.555m

is there 3 sig figs? 5.6 x 10^-12s

2 so false

Perform each calculation to the correct number of sig figs. (568.99-232.1)/5.3

336.9/5.3 = 64

42 a and b

5.50 and 5.6