Answer:
90yrs
Explanation:
Half life is the time taken for half of an original radioactive material to decay by half.
For the sample;
Half - life = 45yrs
Original amount = 600cpm
Start Number of atoms
0yrs 600cpm
First half life
45yrs 300cpm
Second half life
90yrs 150cpm
Kernels of corn are heated and become popcorn. Why is this a chemical change?
Answer:
When popcorn is popped, liquid inside the kernel is changed to steam. Pressure from the steam builds up inside the kernel. When the pressure reached a critical stage the kernel pops turning itself inside out. This is a physical change.
Explanation:
plz help me and fast
Answer:1.atoms give one or more electrons with each other to form the bond
2. Each atom is left with a complete outer shell
3. A covalent bond forms between two
nonmetals
Explanation:
Chemistry, biology and geography are the branch of natural science.
Select one:
True
False
Answer:
the answer is (a)true.
Answer (s) true.
Explanation: Natural science can be divided into two main branches: life science and physical science. Life science is alternatively known as biology, and physical science is subdivided into branches: physics, chemistry, astronomy and Earth science.
Which example is a body fossil?
shrimp burrow
dinosaur bone
dinosaur footprint
an ornithopod track
Answer: B. dinosaur bone
Explanation: Took the test hope this helps! :)
Temperature and kinetic energy have a relationship.
Answer:
[tex]\boxed {\boxed {\sf Temperature=Average \ kinetic \ energy}}[/tex]
Explanation:
Temperature is also known as the average kinetic energy in a substance.
If there is an absence of heat in a substance, the particles move slower and the kinetic energy decreases. The temperature will be lower, because there is less kinetic energy.
If heat is present or applied, the particles move more, so kinetic energy increases. The temperature will be higher, since there is more kinetic energy.
So, the relationship is: temperature is the measure of average kinetic energy.
Answer:
DIRECT
Explanation:
PLEASE HELP WITH THESE THREE (30 POINTS)
1) How is the number of neutrons in the nucleus of an atom calculated?
A. Add the number of elections- and protons+ together
B. Subtract the number of elections- from protons+
C. Subtract the number of protons+ from the atomic mass number
D. Add the atomic mass number to the number of elections-
2) Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr) are in the same group on the periodic table. Why? *
A. They have the same size.
B. They react with each other.
C. They have similar properties.
D. They have the same number of protons
3) Which of the following elements would be a transition metal?
A. Ca
B. Au
C. Rb
D. Fr
Calculate the mass of fe(no3)3 that is measured to prepare 500.0 mL of a 0.175mol/L solution.
Answer:
21.3g
Explanation:
The formula of the compound is;
Fe(NO₃)₃
Given:
volume = 500mL = 0.5L
concentration = 0.175mol/L
Unknown:
Mass of Fe(NO₃)₃ measured = ?
Solution:
To solve this problem, find the number of moles first;
Number of moles of Fe(NO₃)₃ = concentration x volume
So;
Number of moles = 0.175 x 0.5 = 0.088mol
Now to find the mass;
Mass = number of moles x molar mass
Molar mass of Fe(NO₃)₃ = 55.8 + 3[14 + 3(16)]
Molar mass of Fe(NO₃)₃ = 55.8 + 3(62) = 241.8g/mol
Mass = 0.088mol x 241.8g/mol = 21.3g
Moritz is watching his little brother play in a mud puddle. Moritz notices that when his brother stirs it with a stick, after a few moments the dirt settles back to the bottom of the puddle. His brother is creating a . Anjali knows that whole milk has more fat than skim milk. However, the solid fat doesn’t seem to separate from the liquid milk even after it has been in the fridge for a few days. This is evidence that milk is a .
Answer:
1. suspencion
2.colloid
Explanation:
Answer:
Moritz is watching his little brother play in a mud puddle. Moritz notices that when his brother stirs it with a stick, after a few moments the dirt settles back to the bottom of the puddle. His brother is creating a SUSPENSION.
Anjali knows that whole milk has more fat than skim milk. However, the solid fat doesn’t seem to separate from the liquid milk even after it has been in the fridge for a few days. This is evidence that milk is a COLLOID.
Which orbital can be modeled by a "peanut" shape?
Answer:
d - orbital
Explanation:
The d-orbital can modelled by a peanut shape.
A peanut shape closely resembles the shape of a double dumb-bell shape. The double dumb-bell shape is like that of a peanut.
The s-orbital has a spherical shape. p - orbital is dumb-bell shapedd - orbital is a double dumbellf - orbital has a complex shape.Therefore, since a peanut is like a double dumb-bell, it clearly models the d-orbital.
Tin-126 has a half life of 100,000 years. How many years does it take to
reduce 100 g of Tin-126 to 12.5 g?
100,000 years
200,000 years
50,000 years
300,000 years
Answer:
300,000 years
Explanation:
100g=0 years
50g=100,00 years
25g=200,00 years
12.5g=300,000 years
20 PTS!!! Jack said that unprocessed oil is a mixture of many organic compounds. Jane said that unprocessed oil needs to be processed so that individual compound can be isolated. Who made the correct statement and why?
1. Jack is correct, unprocessed oil is a mixture of many organic compounds. Jane is not correct, they do not need to be processed to be used.
2. Jack is incorrect, unprocessed oil is not a mixture of many organic compounds. Jane is correct, unprocessed oil needs to be processed to be used.
3. Both Jack and Jane are correct. Unprocessed oil, petroleum, is a mixture of organic compounds that need to be isolated or separated to be used.
4. Neither Jack nor Jane are correct. Unprocessed oil, petroleum, is not a mixture of organic compounds and it does not need to be isolated or separated to be used.
Answer:
Explanation:
i am thinking 3 and 2 but i am gonna say it is 2
98.654321%
Answer:
Both Jack and Jane are correct. Unprocessed oil, petroleum, is a mixture of organic compounds that need to be isolated or separated to be used.
Explanation:
Which of these items found on a food label IS NOT a food?
Calories
Sugar
Proteins
Total fats
Answer:
the first one Calories
QUESTION 8: When would acceleration increase most? *
2 points
Rolling along a flat plane
Rolling down a steep hill
Braking to a stop
Rolling up a gently sloping hill
Answer:
Rolling down a steep hill
Explanation: