Answer: The footprints were made [tex]2.99\times 10^6years[/tex] years long ago.
Explanation:
Radioactive decay follows first order kinetics.
Half-life of isotope X= 500,000 years
[tex]\lambda =\frac{0.693}{t_{\frac{1}{2}}}=\frac{0.693}{500000}=0.00000139year^{-1}[/tex]
The equation for first order kinetics is :
[tex]N=N_o\times e^{-\lambda t}[/tex]
N = amount left after time t = 0.125 mg
[tex]N_0[/tex] = initial amount = 8.00 mg
[tex]\lambda[/tex] = rate constant
t= time
Putting the values we get:
[tex]0.125=8.00\times e^{- 0.00000139years^{-1}\times t}[/tex]
[tex]0.0156=e^{- 0.00000139years^{-1}\times t}[/tex]
[tex]t=2.99\times 10^6years[/tex]
The footprints were made [tex]2.99\times 10^6years[/tex] years long ago.
Nuclear energy is currently used in which three kinds of vehicles?
Answer:
A. cars, submarines, spacecraft
Explanation:
I took the test.
How many protons are there in a neutral, stable Hydrogen atom that makes up 99.985% of the element?
A. 1
B.2
C.3
D.4
E.0
write the molecular fotmula of water
Answer:
H20
Explanation:
Answer:
hope it helped you
Explanation:
H2O (u have to write ✍️no 2 below H.
Friendship is delicate as a glass, once broken it can be fixed but there will always be cracks. Two persons cannot long be friends if they cannot forgive each other's little failings. We all lose friends.. we lose them in death, to distance, and over time.
Answer:
make a new friend if you lose one, Its part of life losing people thats what make us people grow and be more mature.
The mass of an object is 24g and the volume of the object is 16 mL. Calculate the
density of the object?
Answer:
D = m/v
Explanation:
So m = 24g and v = 16mL. (I assume these are the units being used). Then, we get D = 24g/16mL which is 1.5 g/mL
Infer Why is a mechanism needed to remove carbon
dioxide gas from your cells?
Answer:
Because too much Carbon Dioxide can kill us.
Explanation:
two disadvantages of series connection?
Answer:
1- if one component in a series circuit fails, then all the components in the circuit fail because the circuit has been broken.
2- the more components there are in a series circuit, the greater the circuit's resistance
Which statement is not
true?
A. Protons are positive and neutrons are
neutral
B. Electrons have the most mass of the
subatomic particles
C. Protons and Neutrons are found in the
nucleus
Electrons are found outside the nucleus
and have a negative charge
Answer:
B. Electrons have the most mass of the
subatomic particles
Compared to the mass of neutron and proton, mass of electron is negligible.
Answer:
B
Explanation:
when creating a Bohr model, you will usually mark protons + or P and neutrons are usually 0 or N.
Electrons are on the rings surrounding the nucleus, but everything else is inside.
Electrons are typically represented by - or E
Sodium has______ Valence electrons and bismuth has ________ electrons
Please help ASAP on market as brainlister
Answer:
Sodium has 1 valence electron and bismuth has 83 electrons (5 valence electrons)
Explanation:
when is an object in free fall
Answer:
a free-falling object is an object that is falling under the sole influence of gravity. That is to say that any object that is moving and being acted upon only be the force of gravity is said to be "in a state of free fall." Such an object will experience a downward acceleration of 9.8 m/s/s.
You can separate air into two different substances by density. What is air?
O A. A mixture
OB. A compound
C. An atom
D. An element
SUB
Explain what a cold front is.
Answer:
A cold front is a boundary or zone that separates two air masses. The cooler more dense mass replaces the warmer.
hope this helps :)
Explanation:
Answer:
A cold front is a boundary or zone that separates two air masses. The cooler more dense mass replaces the warmer.
Explanation:
i am smart.....( i think )
It is found that after 24!hours 1/8 of the mass of a sample of a radio-active isotope remains What is the half-life of this isotope?
Answer:7.72 years
Nuclear half-life expresses the time required for half of a sample to undergo radioactive decay.
Explanation:
0.01 = 67.0 ×[tex](\frac{1}{2}) ^{\frac{98.0} {1/2 } }[/tex] [tex]\frac{0.01}{67.0}[/tex] = 0.000149=[tex](\frac{1}{2}) ^{\frac{98.0} {1/2 } }[/tex]
[tex]^{\frac{98.0} {1/2 } }[/tex] =log[tex]_{0.5}[/tex] (0.000149)=12.7
[tex]^{\frac{98.0} {1/2 } }[/tex]=7.72 years
Hope this helps have a great day/afternoon :)
Selena is learning about how engineers choose metals for spacecraft. She discovers that spacecraft engineers often mix other metals with titanium. Titanium is a metal that is both lightweight and strong. It also resists corrosion. Selena wants to compare titanium with other metals. She looks at the cell from the periodic table that represents titanium.
Explain what each of the four items in the cell represents. Then, classify titanium as an alkali, alkali earth, or transition metal.
Ti is a transition metal.
Further explanationChemical symbol represent element or compound
The elements are arranged in the periodic system
1. 22This is the atomic number of Titanium
The Atomic Number (Z) indicates the number of protons of an element
2. TiThis is the symbol (chemical formula) of titanium
3. 47.90This is the mass number of Titanium
Mass Number (A) = Number of protons + Number of Neutrons
Atomic Number (Z) = Mass Number (A) - Number of Neutrons
4. TitaniumThis is the name of the element
To determine which group, alkaline, alkaline earth or transition it can be seen from the electron configuration
alkali and alkali earth : configuration from orbital 1s-7s
transition : configuration from orbital 3d-6d (Block d)
Electron configuration from Ti : [Ar] 3d²4s²
if we look at the configuration, then Ti is in the d block which is included in the transition metal
Answer:
The answer is 26
Explanation:
I just took the test
Which particle changes to create a positive or negative ion of an atom?
A.proton
B. neutron
C. electron
Answer:
it is alkali
Explanation:
hope it helps you
name the gas formed when metals react with dilute hcl
Answer:
im maybe 80% sure it's hydrogen gas
Answer:
When a metal reacts with dilute hydrochloric acid, it forms a metal chloride salt and hydrogen gas.
An ice cube is placed in a glass of water. Which of the following best explains the
heat transfer?
A: The thermal
is moving
from the water to from the ice cube into the water into the water
causing the
temperature of
the water to
increase.
B: the thermal energy is moving from the water to the ice cube causing the temperature of the water to decrease
C: the thermal energy is moving from the ice cube into the water causing the temperature of the water to increase
D: the thermal energy is moving from the ice cube into the water causing the temperature of the water to decrease.
D: the thermal energy is moving from the ice cube into the water causing the temperature of the water to decrease.
In the human body, a series of chemical reactions results in the making of energy that is used at both the cellular and organismal levels.
In which course would a person most likely study these chemical reactions?
biochemistry
geochemistry
materials chemistry
physical chemistry
Answer:
It is A: biochemistry
Explanation: i seen there was no answer so i took a chance and surprisingly got it correct
Answer:
e correct option is all of the above
Explanation:
Help meh, please !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Answer:
volume of 200mL, density shows it weighs .789 grams for every mL. .789*200= 157.8 grams
Explanation:
Question 3 (4 points)
A dipole bond is formed when electrons are not shared equally in a covalent bond, resulting in a partial negative charge on one end of the
molecule and a partial positve charge on the other end.
O True
O False
Which of the following models best demonstrates the law of conservation of mass??
(LOOK AT THE PICTURES)!!
Answer:
i think its D
Explanation:
The law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so quantity can neither be added nor be removed.
Taking into account the law of conservation of mass,
The Law of Conservation of Matter is also called the law of conservation of mass or the Law of Lomonósov-Lavoisier. This law postulates that "The mass is not created or destroyed, only transformed."
This means that the reagents interact with each other and form new products with different physical and chemical properties than those of the reagents. And this is because the atoms of the substances are ordered differently.
But the quantities of the masses involved in a given reaction must be constant throughout it, that is, they will not have changed in their proportions when the reaction ends. Then the mass before the chemical reaction is equal to the mass after the reaction.
The exception to the rule is nuclear reactions, in which it is possible to convert mass into energy and vice versa.
Finally, the correct answer is option A. because the atoms of the substances are ordered differently, this is the reagents interact with each other and form new products.
Learn more about law of conservation of mass:
https://brainly.com/question/20081187?referrer=searchResultshttps://brainly.com/question/23986198https://brainly.com/question/1341085515
The correct formula for a compound formed from the elements Al and O is
a. AIO.
b. Al2O.
c. Al3O2-
d. AIO3.
e. Al2O3.
How long does one complete orbit of Earth around
the sun take, give the amount in years and days?
Answer:365 days, 5 hours, 59 minutes and 16 seconds.
Please answer correctly !!!!!!! Will mark brainliest !!!!!!!!!!!!
I beleive it would be 0.8
the volume of water alone is 4.8
the volume of rock and water is 5.6
you would subtract them both to find the volume of the Rock.
I WILL GIVE U BRAINLIEST!!!!!!!
Answer:
I think its b. if not sorry but its the one that makes most sense
Explanation:
Answer:
B
Explanation:
Hope this helps you have a nice day!
How can you tell if an element is a metal or a nonmetal??
Answer:
Elements to the left of the line are considered metals. Elements just to the right of the line exhibit properties of both metals and nonmetals and are termed metalloids or semimetals. Elements to the far right of the periodic table are nonmetals. The exception is hydrogen (H), the first element on the periodic table.
Explanation:
Answer:
looking at its metallic luster
Explanation:
Elements may be classified as either metals or nonmetals based on their properties. Much of the time, you can tell an element is a metal simply by looking at its metallic luster, but this isn't the only distinction between these two general groups of elements. Most elements are metals.
A mixture that is uniformly mixed is called __. a homogeneous b heterogeneous c suspension d colloid
Answer:
a. homogenous
Answer: A. homogeneous
Explanation: A mixture that is uniformly mixed is called homogeneous.
Plz mark brainliest:)
Can y’all look at this and help please
Answer:
2, 3, 4, 5
Explanation:
Pretty sure protons matter a lot unless in acid and bases but ignore this. Atoms mostly empty space as electrons are reeeeeeeeeeaaaallllllyyyy far apart. number of electrons change it is an ion and neutrons change pretty sure its an isotope. Electrons are stupidly small and fast so they don't really count towards the weight. Most mas comes from neutrons and protons in the nucleus
Answer:
2,3,4,5
1st is wrong cuz if u change the number of proton it would change the atomic number which results in different element
6th is wrong because most mass of the atoms come from neutrons and protons collectively so if it would have said THE ATOMS MASS MOSLTY COMES FROM NUCLEONS then u could mark it right
what is octane number
Answer:A measure of performance of fuel for internal combustion engines. Stated simply, a higher octane rating corresponds to more engine power and less knocking or other pre-ignition problems.
Explanation:
I'm also in chemistry.
Answer:
Explanation:
figure indicating the antiknock properties of a fuel, based on a comparison with a mixture of isooctane and heptane.
When 3.00 grams of methane, CH,, reacts according to the balanced equation below, how many molecules of water are produced?
CH, + 202 - CO2 + 2H20
Answer:
2.41×10²³ molecules of water
Explanation:
Given data:
Mass of methane = 3 g
Molecules of water formed = ?
Solution:
Chemical equation:
CH₄ + 2O₂ → CO₂ + 2H₂O
Number of moles of methane:
Number of moles = mass/ molar mass
Number of moles = 3 g/ 16 g/mol
Number of moles = 0.2 mol
Now we will compare the moles of water with methane.
CH₄ : 2H₂O
1 : 2
0.2 : 2 × 0.2 = 0.4 mol
Molecules of water:
1 mole = 6.022×10²³ molecules of water
0.4 mol ×6.022×10²³ molecules of water / 1mol
2.41×10²³ molecules of water