Answer:
60 hours
Explanation:
18.0 __15__ 9 __15__ 4.5 __15__ 2.25 __15__ 1.125g
15(4)= 60
Sodium-24 has a half-life of approximately 15 hours. If only one-eighth of the sodium-24 remain , then it has been passed in 60 hours. So option D is correct.
What is half life and decay law ?The time required for half of the original population of radioactive atoms to decay is called the half-life. The relationship between the half-life, T₁ ÷ 2, and the decay constant is given by T₁/2 = 0.693/λ
According to radioactive decay law, the rate of decay of radioactive atoms at any instant is directly proportional to the number of atoms present at that instant.
dtd N ∝ N
dtd N = λ N
where, N is number of integrated nucleus present in the sample at any time t and λ is decay constant.
Thus ,option D 60 hours is correct.
To learn more about half life follow the link below :
https://brainly.com/question/16387602
#SPJ2
“Chemistry is the study of all substances. Chemistry is everywhere” you think this is a good enough answer for a test about “what is chemistry?
Answer:
Try to make it more detailed "Chemistry is the study of all substances" is an amazing start. Can you give some examples of chemistry? Try to make a small paragraph.
Explanation:
Explanation:
Chemistry, the science that deals with the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes.
This is a more detailed answer...
Which of the following is the correct Lewis Dot Structure for MgBr2?
PHOTO ABOVE
Answer:
Option A
Explanation:
To know the correct answer to the question, let us write an equation illustrating the formation of MgBr₂.
This is illustrated below:
1. Magnesium (Mg) is divalent element hence it will lose 2 electrons to form magnesium ion (Mg²⁺) as shown below
Mg —> Mg²⁺ + 2e¯
2. Bromine (Br) is a univalent element. Two bromine atom will receive the two electrons (i.e each atom receives 1 electron) to form the bromide ion (Br¯) as shown below:
2Br + 2e¯ —> 2Br¯
Combine both equation
Mg + 2Br + 2e¯—> Mg²⁺ + 2e¯ + 2Br¯
Cancel out 2e¯
Mg + 2Br —> Mg²⁺ + 2Br¯
Thus we have
Br—Mg—Br
From the illustration made above, we can see that two bromine atom is receiving 1 electron each from the magnesium atom
Calculate the mass of the following:
9.11 mol He
Answer:
36.44 g of He
Explanation:
To convert from moles to grams, you simply multiply by the atomic mass. The conversion table looks like the following:
[tex]\frac{9.11 mol}{1}[/tex] * [tex]\frac{4.00 g}{1 mol}[/tex]
The mol units then cancel, and you are left with 36.44 g of Helium.
A bar of metal with a volume of 12.0 cm^3 has a mass of 136 g. What us the density of this metal?
Answer:
The answer is 11.33 g/cm³Explanation:
The density of a substance can be found by using the formula
[tex]density = \frac{mass}{volume} \\[/tex]
From the question
mass = 136 g
volume = 12 cm³
We have
[tex]density = \frac{136}{12} = \frac{34}{3} \\ = 11.333333...[/tex]
We have the final answer as
11.33 g/cm³Hope this helps you
What information does a radioactive element's half-life tell you about that element?
Kendra conducts an experiment. She mixes two chemicals, resulting in a chemical reaction. Based on Kendra's
experiment, what can be concluded about the original matter before mixing?
It did not change in identity but did change properties.
It changed in identity but not properties.
It changed in identity and properties.
It did not change in identity nor properties.
Answer: It changed in identity and properties.
Explanation:
Answer:
C: It changed in identity and properties
Explanation:
Hope this helps! good luck :)
Curiosity is important in the progress of science because it
A. aids in the interpretation of data.
B. encourages new experimentation.
C. ensures the inclusion of different viewpoints.
D. allows a scientist to learn from others.
Answer:
B
Explanation:
because it makes you want to know what happens in an experiment
Answer:
B. encourages new experimentation.
Explanation:
right on EDGE 2021
brainliest plz YW ppl
A sample of ink is put in the center of filter paper . Several drops of ethanol are then put on the ink mark. Two concentric rings of circle are obtained. What is the best conclusion about the ink we can come to? a. It contains two colored substance only b. It contains at least two coloured substances c. It is a compound d. It is broken down by ethanol
Answer:
The correct option is;
b. It contains at least two colored substances
Explanation:
In chromatography, a mixture is separated into its components, such that in the filter paper, on which the drops of ethanol are then placed on the ink mark, we have different phases of the components of the mixture that have different levels of mobility by capillary action through the filter paper. Therefore, given that two concentric rings of circles are obtained, we have that each ring is composed of a different component of the mixture and there are therefore, at least two colored substances.
two types of tests you could perform to determine if a substance was a metal or nonmetal.
The easiest easy to find about metal is through the periodic table. Most of the ele,mtns are metals and the only exception is hydrogen which is nonmetal as it's in its gaseous state.
Hence about 75% of the elements are metals. Many metals ending has ium. Like lithium, titanium and non metals have endings with gen such as oxygen, hydrogen, and argon. Metals are ductile can be drawn into wire form. Metals have a luster that is they reflect Metals are good conductors of heat and electricity. Thus these are some of the methods to test.Learn more about the tests you could perform to determine if a substance was a metal or nonmetal.
brainly.com/question/11493240.
Describe a few abiotic factors found within the taiga that limit its biodiversity.
Answer:
Some abiotic factors of the taiga are temperature, precipitation, soil, and sunlight.
Explanation:
emperature affects the taiga because the winter temperature range is -65*F to 30*F (-54*C to -1*C), while the temperature range in the summer is 20*F to 70*F (-7*C to 21*C)
Precipitation affects the taiga because there's some precipitation that falls [30-85 cm. (12-33 in.)].
Soil affects the taiga because there's some acidic and low-in-nutrients soil, and some fertile soil.
Sunlight affects the taiga because there are small amounts of it that reach the ground.
The taiga biome's abiotic components include temperature, sunshine, soil, air, water, etc. Cold arctic air predominates in the taiga environment. The taiga receives more light in the summer, which causes the days to be hotter.
What are abiotic components ?Abiotic elements, also known as abiotic factors, are non-living chemical and physical elements of the environment that have an impact on the health of living things and the operation of ecosystems. Biology as a whole is supported by abiotic causes and the phenomena that go along with them.
Biotic and abiotic components, such as rainfall, in that order. The taiga is the biggest biome on Earth's surface and features a diversity of migratory and resident creatures. It also has long, cold, and dry winters and short, warm, and moist summers.
The Taiga biome is restricted by four primary criteria. Fire, temperature, the quantity of nutrients in the soil, and sunshine are the four limiting elements. Because certain plants, like the Jack Pine, recover after fire, it is a limiting element in the Taiga biome.
Thus, The taiga biome's abiotic components include temperature, sunshine, soil, air, water, etc.
To learn more about abiotic components, follow the link below;
https://brainly.com/question/13500413
#SPJ2
how many significant figures in 1. 19.99 2. 140486 3. 0.0609 3. 5.08 ?
1. 4 significant numbers
2. 6 significant numbers
3. 3 significant numbers
4. 3 significant numbers
Further ExplanationSignificant numbers are numbers obtained from the measurement results of exact numbers and the last number estimated
1. 19.99
all non-zero numbers are significant numbers , so there are 4 significant numbers
2. 140486
a zero which is located between two non-zero numbers including a significant number , so there are 6 significant numbers
3. 0.0609
a zero in front of a decimal point is not a significant number, so there are 3 significant numbers (6,0 and 9)
4. 5.08
Any zeros between two non-zero numbers are significant, so there are 3 significant numbers(5,0 and 8)
23. Color of a metter is
Are carbon atoms a pure substance or a mixture?
Answer:
Substance
Explanation:
Answer: Substance
Explanation:Ex: Hydrogen gas is a pure substance, as it is made up of only Hydrogen atoms or molecules. Carbon, gold, & nitrogen are other elements (pure substances).
Describe the way matter is measured
Answer:
in volume in weight and distibution
Explanation:
Four substances have the physical properties shown.
Which substance is an ionic solid?
melting point
1 °C
boiling point
1°C
electrical
conductivity
of solid
electrical
conductivity
of molten
substance
electrical
conductivity
of aqueous
solution
A
-115
-85
poor
poor
good
B
660
2470
good
good
insoluble
с
993
1695
poor
good
good
D
1610
2230
poor
poor
insoluble
Answer:
the answer is the location of the WORLD is the same as the answer to the answer
A chemical reaction takes place to allow hand warmers to give off heat. This is an example of a(n) __________.
A. physical change
B. exothermic reaction
C. endothermic reaction
D. precipitate
Answer:
Exothermic
Explanation:
Exothermic reactions release heat, endothermic absorb heat, and precipitate is a solid formed from a solution
Answer:
B.
Explanation:
Gives off heat,.
how do i find out the subscripts of an ionic compound?
Answer:
1. Write the symbol and charge of the cation (metal) first and the anion (nonmetal) second. 2. Transpose only the number of the positive charge to become the subscript of the anion and the number only of the negative charge to become the subscript of the cation
To find out if the height from which a student drops a ball affects how high the ball bounces, the independent variable is the
Answer:
The independent variable is the height of the ball that bounces.
the scientefic methos is founded on
Answer:
Francis Bacon was the first to formalize the concept of a true scientific method, but he didn't do so in a vacuum. The work of Nicolaus Copernicus (1473-1543) and Galileo Galilei (1564-1642) influenced Bacon tremendously.
The half-life of Zn-71 is 2.4 minutes. If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed?
7.2 / 2.4 = 3 half-lives
(1/2)3 = 0.125 (the amount remaining after 3 half-lives)
100.0 g x 0.125 = 12.5 g remaining
What is the quickest way to dissolve milk in water? Can milk dissolve in all
solvents? Explain your answer.
It dissolves in hot water because of the water temperature, the milk could not take it to mix in the hot water
Which set of coefficients will balance this chemical equation?
__C2H4 + __02 - 2 CO2 + 2 H2O
A. 2,5
B. 1,3
C. 1, 2
D. 2,3
Answer:
Option B is correct = 1,3
Explanation:
Chemical equation:
C₂H₄ + O₂ → CO₂ + H₂O
Balanced chemical equation:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
Step 1:
Left side Right side
C = 2 C = 1
H = 4 O = 3
O = 2 H = 2
Step 2:
C₂H₄ + O₂ → 2CO₂ + H₂O
Left side Right side
C = 2 C = 2
H = 4 O = 5
O = 2 H = 2
Step 3:
C₂H₄ + O₂ → 2CO₂ + 2H₂O
Left side Right side
C = 2 C = 2
H = 4 O = 6
O = 2 H = 4
Step 4:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
Left side Right side
C = 2 C = 2
H = 4 O = 6
O = 6 H = 4
A student noticed a yellow, solid substance was formed when mixing two clear liquids during a lab. What term describes this yellow, solid substance?
A. physical change
B. exothermic reaction
C. endothermic reaction
D. precipitate
Answer:
D
Explanation:
a precipitate is formed from a solution
According to Coulomb's law, what will happen to the electric force between
two identical negative charges as they move closer together?
A. F, will stay positive and increase in magnitude,
B. Fe will stay negative and increase in magnitude,
C. F, will become negative and decrease in magnitude
0
D. F will become positive and decrease in magnitude,
SUS
Answer:
A
Explanation:
Apex
How many reflector surfaces does a radio telescope have?
Answer:
I believe 2
Explanation:
Primary parabolic reflector and the sub reflector
anyone know this? I'll brainlist u!
Answer:
for the second one i'd go with reflection
Explanation:
1.) Nonmetallic elements form ions by (Losing/Gaining) valence electrons in order to complete their outer shell. 2.) The (Fewer/More) valence electrons an element has in its outer shell, the easier it is to complete. 3.) The (FewerMore) electron shells an element has, the easier it is to fill its outermost shell. 4&5.)Reactivity in nonmetals (Increases/Decreases) as you go from left to right in a group, and (Increases/Decreases) as you go from top to bottom.
Answer:
1) Gaining
2) More
3) More
4) increases
5) decreases
Explanation:
Nonmetals are found towards the right hand side of the periodic table. They form ions by gaining electrons due to the fact that they have more electrons in their outermost shell, hence they only need a few electrons to complete the octet structure.
As the number of shells increases, the outermost shell becomes more populated and easier to fill with electrons.
The reactivity of nonmetal elements generally increases from left to right across the periodic table but decreases from top to bottom down the group.
Answer:
1) Gaining
2) More
3) fewer
4) increases
5) decreases
Explanation:
will someone help me, marked as brainiest
Answer:
C
Explanation:
Answer:
c.metal
Explanation: metal is able to carry heat
Which pattern(s) may be observed from the arrangement of elements in the periodic table? Select all that apply.
A. increasing number of protons
B. similarity in the number of their valence electrons
C. similarity in their physical and chemical properties
D. increasing relative abundance on Earth's surface
Answer:
A, B, C.
Explanation:
The periodic table exemplifies the number of protons for each element, the number of valence electrons for each element, and depending on the specifications and the complications of the periodic table (in other words the higher quality of a periodic table) will also commend upon you physical and chemical properties of each element and each group of which they belong to. Hopefully this helps.
The pattern(s) may be observed from the arrangement of elements in the periodic table -
A. increasing number of protonsB. similarity in the number of their valence electronsC. similarity in their physical and chemical propertiesThe periodic table has various types of patterns in their arrangement of elements.
As you move to the right, the atomic number increases, meaning the number of protons increases.The number of valence electrons decreases from left to right across each period.The number of valence electrons increases from top to bottom within each groupEach element within a group has similar physical or chemical properties because of its atom's outermost electron shellThus, the correct choices are - A, B, and C.
Learn more:
https://brainly.com/question/7373020
Which of the following is a fossil fuel?
A. oil
B. Copper
C. aluminum
D. Cattle
Answer: oil
The answer is A, oil. Oil is one of the most popular fossil fuels. You probably did not know the answer was fossil fuels. The answer is oil.
Hope this helps you!