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Knewton’s assessment Test Questions Solved 100% Correct |Verified Answers
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Knewton’s assessment Test Questions Solved100% Correct |Verified Answers
If you boil an entire sample of water, the steam that results will have: - Answer the same
mass as the water
Through the complete electrolysis of a sample of pure water, a student collects 14.0
grams of hydrogen gas and 112.0 grams of oxygen gas. What mass of water (in grams), if
it reacted completely, was initially present? (The electrolysis of water is the use of an
electric current to decompose it into its component elements.) - Answer 126.0 g
Which of the following CANNOT be classified as a compound?a. carbon dioxideb.
sodium chloridec. lithiumd. sugar - Answer c. lithiumLithium is an element. The rest
are made of multiple elements.
The nucleus of an atom can be split into smaller components by what kind of process? -
Answer none of the above:
a physical or chemical process or melting
- The nucleus of an atom cannot be split into its components by either a physical
or chemical change. Splitting an atom is a nuclear process.
If something is a compound, it is also - Answer a pure substance
- Pure substances are either elements or compounds. A compound is a pure
substance composed of more than one element.
,A compound is a chemical substance composed of two or more kinds of elements in a
fixed ratio. By what means can the components of a compound be separated? -
Answer Chemical means
- A compound cannot be separated into its component elements by physical means,
but it can be separated into its component elements by chemical means.
The ampere is the base unit for electric current in what metric system? - Answer SI
- The ampere is the base unit for electric current in the SI system.
Mass depends on: - Answer the amount of material
- Mass is an extensive property, which means it depends on how much of a substance
there is.
Which of the following units is a derived SI unit (not one of the SI base units)? - Answer
newton
- Newtons are defined to be kg ms2. The other three units are base SI units.
Today, the meter is based on: - Answer the distance light travels in a particular
fraction of a second
- The meter was once defined as a particular fraction of the distance from the
equator to the north pole, but it was eventually revised to be more universal.
,The volume of a 12.4 g metal pellet is measured by water displacement. It is added to
a graduated cylinder filled with water, and the level rises from 10.00 mL to 13.65 mL.
What is the density of the metal? - Answer 3.4 g per mL
- Use a systematic approach to solve the problem.1. Read the problem carefully: Note
that the pellet's volume is being found by the change in total volume when it is added to
a sample of water.2. Identify the given information: The given mass is 12.4 g. The
starting volume (the volume of the water) is 10.00 mL. The final volume (total) is 13.65
mL.3. Identify what is being asked for: The question is asking for the density in grams
per milliliter.4. Identify intermediate steps: Density is mass per volume, or d=mV. Since
the mass is known, the volume of the pellet is needed, and it can be found from the
change in volume read from the graduated cylinder.
Vpellet=Vfinal−Vinitial
.5. Find the answer: Find the volume of the pellet.
Vpellet=13.65 mL−10.00 mL=3.65 mL
Next, substitute the mass and volume of the pellet into the formula for density.
d=mV=12.4 g3.65 mL=3.3973gmL
The answer should be rounded to one decimal place, so round to 3.4gmL.6.
Check answer reasonableness: A density of 3.4gmL is reasonable for metal.
A cube with a mass of 250.0 g has sides measuring 5.00 cm each. What is the density
of this cube in grams per cubic centimeter? - Answer 2.00 grams per cubic centimeter
A 1.00 m long beam of stainless steel with a square 2.00 cm×2.00 cm cross section has
a mass of 3.02 kg. What is its density in grams per cubic centimeter? - Answer 7.55
grams per cubic centimeter
, The density of a cube is 2.0gcm3. If the mass is 128 g, what is the length of each side
of the cube? - Answer 4.0 cm
To calculate the length of each side of the cube we must first calculate the volume of
the cube. We can use the equation d=mV, where d is the density, m is the mass and V is
the volume. Rearrange the equation to solve for V and substitute the given values into
the equation to calculate the volume.
V=md=128g2.0gcm3=64cm3
Since the volume of a cube is equal to the length of a side cubed, take the cube root of
the volume to find the side length.
length=64 cm3−−−−−−√3=4.0 cm
The density of an unknown crystal is 2.65gmL. If a 4.46 g sample of the crystal is
added to a graduated cylinder containing 25.0 mL of water, what will the volume
read? - Answer 26.7 mL
- Use a systematic approach to solve the problem.1. Read the problem carefully: Note
that the crystal is added to the water and the total volume will represent the volume
of the water and the volume of the crystal.2. Identify the given information: The given
density is 2.65gmL, the mass is 4.46 g, and the volume of the water (Vw) is 25.0 mL.3.
Identify what is being asked for: The question is asking for the total volume in milliliters
(Vtot).4. Identify intermediate steps: The total volume (Vtot) will be the volume of the
water (Vw) plus the volume of the crystal Vc.
Vtot=Vw+Vc
So the volume of the crystal is needed. To find the volume of the crystal, use
the definition of density, d=mV, and isolate V.
Vc=md
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