The half-life of strontium-90 is about 29 years. How many half-lives have elapsed when 6.25% of
O 1
02
3
оо
The question is incomplete, the complete question is;
The half-life of strontium-90 is about 29 years. How many half-lives have elapsed when 6.25% of a strontium- 90 sample remains in the container?
Answer:
4 half lives
Explanation:
From;
N/No = (1/2)^t/t1/2
N= amount of strontium-90 present at time t
No= amount of strontium-90 originally present
t= time taken
t1/2 = half life of strontium-90
But N= 0.0625No
Hence;
0.0625No/No = (1/2)^t/29
0.0625 = (1/2)^t/29
(1/2)^4 = (1/2)^t/29
4 = t/29
t = 4 × 29
t= 116 years
Hence four half lives have elapsed
examples of metal non-metal and semi metal
Answer:
Semi : Boron [B] Non-Metal : Carbon [C] Metal : Manganese [Mn]
Explanation:
Periodic table I'm guessing!
Which prefix indicates a molecule with 2 carbon atoms?
O A. Eth-
O B. Oct-
O c. Hex-
O D. Meth-
The answer is A.Eth-
The prefix indicates a molecule with 2 carbon atoms is eth- and the correct option is option A.
What is IUPAC Nomenclature?
The IUPAC system of nomenclature is a set of logical rules framed which are mainly aimed at giving an unambiguous name to an organic compound.
IUPAC stands for International Union of Pure and Applied Chemistry
A prefix to the name comes before the molecule. The prefix of the molecule's name is based on the number of carbon atoms.
For example, a chain of six carbon atoms would be named using the prefix hex-.
The suffix to the name is an ending that is applied that describes the types of chemical bonds in the molecule.
Therefore, The prefix indicates a molecule with 2 carbon atoms is eth- and the correct option is option A.
Learn more about IUPAC Nomenclature, here:
https://brainly.com/question/30086566
#SPJ7
PLEASE HELP!!
What is the reduction half-reaction for 2Mg + O2 —> 2MgO?
A) Mg -> Mg2+ + 2e-
B) O2 + 4e- -> 2O2-
C) Mg2+ + 2e- -> Mg
D) 2O2- -> O2 + 4e-
Answer:
O2 + 4e- -> 2O2-
Explanation:
You have to start by assigning the oxidation numbers, which eventually will lead to every atom of oxygen taking 2 electrons and every molecule of oxygen will take 4 electrons.
(you can ignore this explanation, my answer wasn't long enough).
PLEASE HELPP!!
What is the empirical formula of the compound is C22H44O22
A. CH2O
B. C3H6O3
C. C2H4O2
D. CHO
Answer:
The answer is C
A3B8 + C2 ---> AC2 +
B2C
1. What is the balanced equation for the combustion reaction?
Answer:
A₃B₈ + 5C₂ –> 3AC₂ + 4B₂C
Explanation:
A₃B₈ + C₂ –> AC₂ + B₂C
The equation can be balance as illustrated below:
A₃B₈ + C₂ –> AC₂ + B₂C
There are 3 atoms of A on the left side and 1 atom on the right side. It can be balance by writing 3 before AC₂ as shown below:
A₃B₈ + C₂ –> 3AC₂ + B₂C
There are 8 atoms of B on the left side and 2 atoms on the right side. It can be balance by writing 4 before B₂C as shown below:
A₃B₈ + C₂ –> 3AC₂ + 4B₂C
There are 2 atoms of C on the left side and a total of 10 atoms on the right side. It can be balance by writing 5 before C₂ as shown below:
A₃B₈ + 5C₂ –> 3AC₂ + 4B₂C
Now, the equation is balanced.
Which row represents an ion?
number of
protons
number of
neutrons
number of
electrons
А
1
0
1
B
3
4
3
C С
6
6
6
D
11
12
10
Answer:
12123456789012347698
A circuit is set up with two parallel resistors, each of a resistance of 250Ω.
b. If another resistor of resistance 300Ω is added in series with these two parallel resistors, what is the total
resistance?
c. If a voltage of 120V is put across the circuit in b, what will the current be in the circuit?
Answer:
425 and 0.28A
Explanation:
Resistance for resistors in parallel
1/ R = 1/250 +1/250
=0.008
R = 1/ 0.008 = 125
Total resistance
R= 125+ 300
=425
...
V= IR
I= V/R
I = 120/425
= 0.28 A
calculate the oxidation numbers of the elements in this equation
2 Al2O3 → 4 Al + 3 O2
Explanation:
Answer
Open in answr app
The rule used here is that the algebraic sum of the oxidation numbers of all the atoms a molecule is zero.
Al2O32× ( oxidation number of Al)+3× ( Oxidation number of O ) = 0
2× ( Oxidation number of Al) +3(−2)=0
2× ( oxidation number of Al) +6
∴ Oxidation number of Al =+3
list 8 functions of petroleum
Select the statement that is most correct regarding chemical bonds. A. multiple bonds between two atoms are not possible with covalent bonding B. hydrogen bonds are very weak and can only occur when polar covalent bonds are present C. Ionic bonds involve the sharing of electrons D. Covalent bonds involve the transfer of one or more electrons from one atom to another
Answer:
hydrogen bonds are very weak and can only occur when polar covalent bonds are present
Explanation:
Hydrogen bonds are weak intermolecular interactions that occur when hydrogen is covalently bonded to a highly electronegative atom.
Owing to the difference in electro negativity between hydrogen and the highly electronegative atom, the bond is a polar covalent bond.
This hydrogen bond is a weak bond but accounts for properties such as high melting and boiling points of small molecules such as water and ammonia.
what are microorganisms
Please i really wanna know
Answer:
Are the organism we cant see with our bare eyes. We only see them with the help of a microscope
Explanation:
Which of the following represents an element ? H2O H2 NaCl CaCO3
Answer:
H₂
Explanation:
H₂ is hydrogen in its elemental form.
H₂O, NaCl, and CaCO₃ are all examples of elements added together to create compounds.
Describe two situations in which you observed or performed an energy transformation. For each situation, name the starting form of energy and an ending form of energy.
Answer:
The Sun transforms nuclear energy into heat and light energy.
Our bodies converting chemical energy in our food into mechanical energy for us to be able to move.
An electric fan transforming electrical energy into kinetic energy.
You are given 3 unknown solutions with pH value as 6, 8 & 9.5 respectively. Which solution will contain maximum OH ion
A wheelbarrow can be used to help lift a load, such as a pile of dirt, and then push the load across a distance.
A man pushes a wheelbarrow.
Which simple machines make up a wheelbarrow?
a pulley and an inclined plane
a wheel and axle and a lever
a pulley and a wheel and axle
a lever and a wedge
Answer: it consists of two simple machines: a lever and a wheel and axle. Effort is applied to the lever by picking up the handles of the wheelbarrow.
Explanation:
Answer:
B
Explanation:
B)
Geometric isomers have profound effects on the physical properties of compounds. Naturally occurring fatty acids generally adopt a cis geometry. What's one physical property affected by this geometry? (HELP ASAAAP!)
A)
Color
B)
Taste
C)
Smell
D)
Melting point
Answer:
melting point
Explanation:
Vhon Anadome
Atomic nucleus questions
Which of the following decay processes results in the largest change in mass of a nucleus?
Choose 1 answer:
А
Beta decay
Gamma decay
Neutron emission
D
Alpha decay
Answer:
d
Explanation:
What happens to the intensity of light emitted from stars the further away the star is from us?
Answer: stars vary in their effective temperature and colour. A hot star radiates more energy per second per metre surface area than a cooler star. Does this then mean that a hot star is going to appear brighter to us than a cooler one? The answer to this actually depends on a few factors
Explanation: pa brainiest po
Chloe’s teacher gives her and her lab partner soil samples from different parts of the city: the park, the area next to a pond, the school, and a neighborhood. Chloe’s teacher also gives her a soil tester kit, which determines the pH of the soil. Chloe and her lab partner need to determine the pH of each soil sample and then compare them.
Fill in the blank with the word that best completes the statement.
This investigation is a(an)______investigation.
Answer:
an
Explanation:
It is AN because investigation starts with I ( i is a vowel). When there are vowels we use An.
Pls mark me brainliest!
_ As + _ NaOH → _Na3ASO3 + __ H2
Answer:
2As + 6NaOH =2Na3AsO3 +3H2
Explanation:
2As + 6e- = 2As³ ,this is an oxidation reaction
6H¹ +6e- =6H⁰ ,this is reduction process
the above reaction exhibit a redox redox reaction As acts as a reducing agent while NaOH acts as an oxidizing agent.
¿Cuál de los siguientes valores es igual a 1 micrómetro?
O 0,000001 metro
O 0,001 metros
O 1.000 metros
O 1.000.000 metros
the six gas laws ASAP PLS
Based on the enthalpy changes given for the reactions, which reactions are endothermic?
Explanation:
yan po sana makatulong
pa brainliest na din po thanks
A 12 inch object is placed 30 inches in front of a plane mirror
Answer:
12 inches
Explanation:
i got it right in the Same question
[tex]what \: is \: acid \: \: \: {?} [/tex]
meaning:An acid is a chemical substance, usually a liquid, which contains hydrogen and can react with other substances to form salts. Some acids burn or dissolve other substances that they come into contact with.
Answer:
Hope it help you#CarryOnLearning*
5. Gravitational potential energy is found in
(1 Point)
a rubber band pulled back ready to be shot
an apple falling from a tree branch
a boy on a skate board gliding up a ramp
a book held high over a desk
Answer:
A book held high over a desk
Explanation:
Gravitational potential energy, or GPE, is like height energy. The higher up an object is placed, the more GPE it has. Gravitational potential energy is the potential of a certain mass relative to another due to gravity. In this case you have a book held high over a desk and therefore since it's higher up it's going to have more potential energy due to gravity, which is why it has gravitational potential energy. Therefore your answer is "a book held high over a desk".
Which property can be attributed to an ideal gas?
A The particles occupy a significant volume.
B The collisions of the particles are elastic.
C The particles move at different velocities.
D The particles move in definite patterns.
calculate the mass m of 6.50 moles n of kbr m
Answer:
773.51495 grams
Explanation:
1 moles KBr to grams = 119.0023 grams
6.5*119.0023 = 773.51495 grams
At the midpoint of a titration curve ________. At the midpoint of a titration curve ________. The concentration of a conjugate base is twice that of the concentration of a conjugate acid The pH equals the pKa The ability of the solution to buffer is at its least effective The concentration of a conjugate base is 1/2 that of the concentration of a conjugate acid
Answer:
The concentration of a conjugate base is twice that of the concentration of a conjugate acid
Explanation:
This is because at the midpoint, the number of moles of acid equals half the number of moles of base at the midpoint. This means that at the midpoint, half the analyte has been titrated.
Since the concentration of the conjugate acid is half that of the conjugate base at the midpoint, this implies that the concentration of the conjugate base is twice that of the conjugate acid.
Thus, at the midpoint of a titration curve the concentration of a conjugate base is twice that of the concentration of a conjugate acid