Answer:
Explanation:
Purpose of Case Control Studies
To determine whether or not an association exists between a disease and a particular risk factor. To start with a group of people with disease and work back to see whether a possible risk factor may be the cause. It may be the first step in testing a hypothesis.
Styrofoam has a density of 0.075 g/mL. What is the volume of 21.80 g of Styrofoam?
The answer is 290.66 mL
Explanation:
The density of any substance including styrofoam is determined by two main factors: mass (atoms in the substance) and volume (space occupied). Moreover, the volume or mass of the substance can be calculated by using the density as these variables are related. Below I show the process:
density = mass / volume
mass = density x volume
volume = mass / density
volume = 21.80 g / 0.075 g/mL
volume = 290.66 mL
Student was identifying the formula of 1 mole of unknown powder. When it was placed on a scale, it was reading 399.91 g/mol. Which of
the following compounds can it be?
A AI(NO3)3
B. C3H8
C. Fe2(SO4)3
D. CaCl2
Answer: The compound is [tex]Fe_2(SO_4)_3[/tex]
Explanation:
Molar mass is defined as the mass in grams of 1 mole of a substance.
S.I Unit of Molar mass is gram per mole and it is represented as g/mol.
A. 1 mole of [tex]Al(NO_3)_3[/tex] weighs = 26.98(1)+14.01(3)+15.99(9) =212.99 g/mol
B. 1 mole of [tex]C_3H_8[/tex] weighs = 12.01(3)+1.007(8) = 44.1 g/mol
C. 1 mole of [tex]Fe_2(SO_4)_3[/tex] weighs = 55.84(2)+32.06(3)+15.99(12) = 399.91 g/mol
D. 1 mole of [tex]CaCl_2[/tex] weighs = 40.07(1)+35.5(2)= 110.98 g/mol
Thus the compound is [tex]Fe_2(SO_4)_3[/tex]
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8. Two or more forces that cancel each other out are*
A:Net forces
B:balanced forces
C:Unbalanced forces
D:Normal force
Answer:
Balance and Unbalanced.
Look at the diagram of a fuel cell below.
Which parts of the fuel cell do A and B represent?
A. air
B. anode and cathode
C. electrolyte
D. hydrogen and nitrogen
A substance has a mass of 22g and a volume of 13cm3. What is the density of the
substance? *
Answer:
1.69 g/cm³
Explanation:
Mass (m) = 22 g
volume (v) = 13 cm³
density (d) = ?
we know density is defined as mass per unit volume
d = m/v
= 22 / 13
= 1.69 g/cm³
Hope it will help :)
Help plzzz I don’t get to
What do we think is going to happen to
the fly populations over the next 30
days?
Can someone help me over here? I need an negative charge and also another thing is that in a question it asked me to use something that would represent an ion. I’m not sure on what to choose either Hydrogen or Helium but just please send help.
Answer:
You could use a hydrogen anion which has 2 electrons.
Explanation:
An ion is an atom or molecule with a net electric charge because it has more or less electrons compared to the original atom or molecule.
An anion is a negatively charged ion.
A cation is a positively charged ion.
Normally a hydrogen atom has one proton and one electron.
So a hydrogen anion (H-) means that it has one proton and two electrons, which means the positive charge will be +1 and the negative charge will be -2.
Ultimately, giving the entire molecule a net charge of -1 because -2+1 = -1.
(I hope this helps! I am not 100% sure what's the format of this question. Like is it interactive? online? Did you draw all those electrons on the diagram? or were they given? Are the numbers given as well? or did you type those in? So I just tried my best to give you something that might work.)
What is the name for Si3S
Answer:
Silicopropane
Explanation:
What property of water is primary for living organisms? (SC.6.E.7.4) *
1 point
It is odorless.
It does not conduct electricity.
It is tasteless
It is liquid at most temperatures on Earth.
Answer:
It is liquid at most temperatures on Earth.
1. How many atoms are in 2.15 moles of water?
*2. How many atoms of copper are in 12.0 grams?
*3. How many moles of NH3 contain 1.75 x 10^24 molecules of?
4. Determine the number of molecules in 16.75 g of H2O ?
5. Find the formula for a hydrate with 48.8% MgSO4 & 51.2% H2O
6. What is the % by mass of C in Pb(C2H3O2)2?
(Questions with stars just don't make sense to me.)
1.29×10²⁴ atoms are in 2.15 moles of water. Atom is also the smallest piece of substance with chemical element-like characteristics.
What is atom?The smallest unit of matter that may be divided without producing electrically charged particles is the atom. It is also the smallest piece of substance with chemical element-like characteristics. As a result, the atom serves as the fundamental unit of chemistry.
Space makes up the majority of an atom. The rest is made up of a cloud of electrons that are negatively charged surrounding a nucleus that is positively charged made up of protons and neutrons. The behaviour of the electron in an atom can be compared to that of particles surrounding the nucleus.
number of atoms = number of moles ×6.022×10²³
= 2.15×6.022×10²³
= 1.29×10²⁴
Therefore, 1.29×10²⁴ atoms are in 2.15 moles of water.
To know more about atom, here:
https://brainly.com/question/29712157
#SPJ3
In the formation of sodium chloride by the combination of
sodium and chlorine:
Answer:
Na(s) + Cl2(g) = NaCl(s)
How many moles of copper are presnet in 148.2g Ca(OH)2
Answer:
2
Explanation:
.
Explain why Thorium-229 is radioactive
Answer:
Thorium-229 is a very insoluble metal that emits radioactive alpha particles. It is generated by the decay of uranium-233 and has a half-life of 7.340 years.
Explanation:
braliyest please
12 and 24
a. GCF
b. LCM
a.12= 2^2*3
24= 2^3*3
GCF= smallest power of each common factor
GCF= 2^2*3
GCF= 12
b. 12= 2^2*3
24= 2^3*3
LCM = greatest power of each factor involved
LCM= 2^3*3
LCM= 24
bromine
+
calcium iodide ® calcium bromide + iodine
Answer:
Br2 + CaI2 = CaBr2 + I2
Explanation:
Disclaimer: Not sure what you're asking, however, I will provide you with the full balanced equation.
Br2 + CaI2 = CaBr2 + I2
A bone contains 6.25% of Carbon -14 it began with. How old is the bone ?
Answer:
Is there a multiple choice??
Explanation:
What is the answer to this question?
Answer:
Its is C urea if this is correct please make me brainliest
What are the 3 types of chemical reactions?
Answer:
Synthesis reactions. Decomposition reactions. Combustion reactions.
Explanation:
Synthesis reactions. - Two or more reactants combine to make 1 new product
Decomposition reactions. - A single reactant breaks down to form 2 or more products.
Combustion reactions. - A single element or compound combines with oxygen gas releasing energy. This rapid oxidation is called burning.
Faries in the stolen child are significant because
Which three observations are caused by plate tectonics?
Answer:
B. HOPE THIS HELPED SENSI
Explanation:
Which process is an example of a physical change?
Answer:Examples of physical change include changes in the size or shape of matter. Changes of state—for example, from solid to liquid or from liquid to gas—are also physical changes. Some of the processes that cause physical changes include cutting, bending, dissolving, freezing, boiling, and melting
Explanation:
What does a branching tree diagram show?
A. The evolution in the size of organisms
B. The order in which specific traits may have evolved
C. The animal population in a specific time period
D. The rate of extinction of specific traits in living organisms
Answer:
B. The order in which specific traits may have evolved
Explanation:
Which process occurs during transpiration?
A.
During transpiration, water vapor precipitates from plants.
B.
During transpiration, water vapor evaporates from plants.
C.
During transpiration, water vapor condensates from plants.
D.
During transpiration, water vapor collects from plants.
E.
During transpiration, water vapor is absorbed by plants.
Answer:
It should be B
Explanation:
because I just searched it up if I'm wrong I'm wrong
Answer:transpiration just took the test
Explanation:
100%
BEST ANSWER GETS MOST POINTS!
In your lab group you combined vinegar and water and observed the results shown in the picture. Choose ALL of the evidence that supports that a chemical change has occured?
A) A gas is produced.
B) The color changed.
C) Bubbling occurred.
D) The baking soda dissolved.
D) There is a change in the composition of the reactants.
Answer:
B) A gas is produced
Explanation:
Which periodic table has the elements placed in locations that match the information on the flash card?
Answer:
https://quizizz.com/admin/quiz/5902a3fd8d05b2100088880a/cat-1-chemistry-review
Explanation:
Answer:
atomic? hope this helps!
Explanation:
How do you negatively affect the ecosystem of the Great Lakes area?
Answer:
Threats to the Great Lakes' ecosystems, include invasive species, climate change, pollution, and habitat destruction. Climate change affects water temperatures, weather patterns, and lake levels. Pollutants from residential, agricultural, and industrial areas reduce water quality.
Explanation:
I hope this helps answer your question
:D
Answer:
Other human activities that have had an impact on the Great Lakes include intentional water level regulation, man-made alterations such as dredging, diversions, and water withdrawals, which have resulted in earlier thawing of the lakes, lower water levels, and, of course, the spread of industrial waste.
Explanation:
4.) What is atomic number.
Answer: the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
Explanation:
Subscripts are the big numbers written to the left of a chemical formula in a chemical equation
True or false
Answer:
Most probably it's true.
Why is Pluto a dwarf planet?
Group of answer choices
A) it can't clear its orbital path of smaller objects
B) its not round
C) its too far away from the sun
D) it doesn't orbit the sun