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
All of the following undergo hybridization except
A. C
B. Si
C. Mg
D. B
Answer:
C: Mg
Explanation:
Hybridization of atomic orbitals is a fundamental concept introduced by Pauling that describes the mixing of orbitals at an atom which adds a definite direction to the Lewis - shared electron pair or electron chemical - bond concept.
Carbon(C) can hybridized on sp, sp2 and sp3 simply because it's valence shell gives room for it.
For silicon(si), when forming covalent bonds with other atoms, it's 3s and 3p orbitals are mixed with each other to form new hybrid orbitals.
Magnesium in itself doesn't hybridized except in magnesium hydrides.
Boron orbitals(B): when boron forms bonds with three other atoms like borazine, they are hybridized to either the sp2 or hybridized to the sp3 which occurs when boron forms bonds with four atoms just as is in metal borohydrides.
A carbon rod and a copper rod were hit alternately with a hammer. The carbon rod broke into pieces. Which property of carbon does this observation indicate?
Answer:
Brittleness
Explanation:
hope this helps u
Answer:
Carbon is a non metal
Explanation:
Non metals are brittle.
Which of these liquids are solutions? Check all that apply. water salt water soda orange juice coffee
Answer:
salt water, soda, orange juice, coffee
Explanation:
Answer: salt water, soda, orange juice, coffee
Explanation: On Edge!!!!!!!!
_____ are the deepest parts of the ocean floor.
A. Seamounts
B. Trenches
C. Mid-ocean ridges
D. Abyssal plains
Answer:
d
Explanation:
im trying i dont actuly know
The ocean floors are the seafloor or the ocean bottoms are called seabeds. The deepest part of the ocean floor is called trenches. Thus, option B is correct.
What is the classification of ocean floors?The ocean floors are said to be the seabeds that comprise of plains, mountains, and canyons, and are termed submarine relief. It ranges from the continental shelf, slope, rise, abyssal plain, ridges, and trenches.
The continental shelf is the first part and is at the least depth of the ocean floors, while the trenches are present at the greatest depth of the seabeds.
The trenches are the deepest part where the sunlight can not penetrate and ranges from 8000 meters and beyond. They are formed due to tectonic plate activity.
Therefore, option B. the trenches are the deepest part of the ocean beds.
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Why do atoms with greater numbers of protons have greater electronegativity?
Science helPPPPPPPPP MEEEEEEEEE RIGHT NOW
in the liquid state hydrogen is used as a fuel in
Answer:
Space Technology
Explanation:
What is a period on the Periodic Table? *
Each of the horizontal rows from left to right of the Periodic Table.
The columns from top to bottom of the Periodic Table.
The elements that are part of the noble gases.
Answer:
Explanation:En la tabla periódica los elementos están ordenados de forma que aquellos con propiedades químicas semejantes, se encuentren situados cerca uno de otro. Los elementos se distribuyen en filas horizontales, llamadas períodos.
List 2 reasons why metals are such great conductors.
PLEASE HELP THIS IS TIMED
Answer:
the atoms in the metals form a matrix through which outer electrons can move freely.
Explanation:
A flow of charged particles is an electric current. A metal has a built in supply of charged particles that can flow from one location to another- the pool of shared electrons.
List two adaptations the cave glow worm has for capturing prey in a cave
Answer:true
Explanation:
List two adaptations the cave glow worm has for capturing prey in a cave. droos a line of silk to trap palle - silk comes from glands in the mouth. a produces light to lure pret a insects are drawn towards light and get trapped in 3.
Bridget is in science class. Her teacher gives her two unknown substances and asks her to determine their relative pH. She places a piece of red litmus paper into both substances. The litmus paper turns purple when she places it into substance I. The litmus paper turns blue when she places it into substance II.
Which of the following is true about the relative pH of the two substances?
A.
Substance I is an acid and substance II is a base.
B.
Substance I is a neutral substance and substance II is a base.
C.
Substance I is a base and substance II is a neutral substance.
D.
Substance I is a neutral substance and substance II is an acid.
Answer:
Substance I is a neutral substance and substance II is a base.
A compound that contains only carbon and hydrogen that produces carbon dioxide and water when burned is called?
a binary compound
Sorry that I dont have an explanation....its just something that needs memorized :)
Hope this helps! Please correct me if I'm wrong!
What property can be used to determine if a sample is a pure substance or a mixture?
Select one:
color
temperature
melting point
mass
Answer:
Melting point
Explanation:
Pure substances have sharp melting and boiling points while impurities lower the melting point and raise the boiling point
In which of the following scenarios is a chemical change taking place? *
3 points
Quartz crystal fractures when struck.
Sugar dissolves when poured into tea
Liquid water turns to a vapor at 100 degrees Celcius.
Sodium metal reacts with water to form sodium hydroxide and hydrogen gas.
Answer:
The answer to this would be D. Sodium metal reacts with water
The correct option is D. Sodium metal reacts with water to form sodium hydroxide and hydrogen gas.
What is a chemical reaction?A chemical reaction leads to the transformation of a substance. The chemical bonds when bonds between reactants break and form a new chemical bond in products.
Quarts crystal fractures, when struck, is an example of physical change. Sugar dissolved when poured into tea is also a physical change. Liquid water turning to vapor at 100 degrees Celcius is an example of boiling.
When sodium metal reacts with water it will react with water and bonds between sodium and water reacts and will form sodium hydroxide and hydrogen gas.
Na(s) + H2O(aq) → NaOH(l)+ H2(g)
Therefore, The correct option is D. Sodium metal reacts with water to form sodium hydroxide and hydrogen gas.
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carbohydrates are called bio fuels why ?
Answer:
There are so many carbohydrate which acts as bio fuel...Few of them glucose ,Cellulose ,starchtion:as bio fuel...Few of
Part A: Name a system in humans that is similar to one of thejtissue systems of the plant, explain
how they are alike.
Click to add speaker notes
Which of the following is different in two isotopes of the same element?
the number of atoms
the number of electrons
the number of neutrons
the number of protons
Answer:
Different number of neutrons
Explanation:
Isotopes are different versions of an element, in which the only difference is that they have different numbers of neutrons in the nucleus, and therefore slightly different atomic masses.
Please help ASAP !!!!!!!!!
Answer:
A. the speed at which reactants change to products over a given time
Explanation:
The rate of reaction is a measure of the speed of a chemical reaction. In chemical kinetics, the speed at which the reaction occurs is the reaction rate.
The measurement of the reaction rate is based on the disappearance of a reactant or appearance of the product with increasing reaction time. Rate of reaction depends on the: nature of reactants. concentration of the reactants or pressuretemperaturepresence of catalystsunlightSomeone help me pls!
Answer:Warm ocean currents originate near the equator and move towards the poles or higher latitudes while cold currents originate near the poles or higher latitudes and move towards the tropics or lower latitude.
Explanation:
4. The compound iron sulfide can be formed by
filtering b. evaporating heating
a.filtering
C.heating
d. mixing
Answer:
When iron sulfide is exposed to oxygen it reacts rapidly, releasing large amounts of heat.
Explanation:
i took this from my notes- so whatever aligns with that. sorry if this didnt help but i think its genuinely c heating
The bumpy pattern on the soles of shoes is called the tread. Melanie and Keisha are at the store looking at the treads on different basketball shoes. They want new shoes so that they do not slide on the basketball court. Which of these situations produces the most friction between the shoes and the floor?
A girl with greater mass wearing shoes with more tread?
As temperature increase and the volume stays constant, how will the pressure change
Answer:
There will be more collisions and so a greater pressure. The number of particles is proportional to pressure, if the volume of the container and the temperature remain constant. ... Volume is inversely proportional to pressure, if the number of particles and the temperature are constant.
A student in class drops an element on the floor and it shatters quite easily. Which property does this best exemplify?
Answer:
Glass
Explanation:
How is covalent bonding typically explained?
Answer:
Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.
what is the most abundant metal in the earth's crust ?
Answer:
aluminium
Explanation:
I think I'm not Rly sure
Answer:
Aluminium
Explanation:
Percent abundance of given elements in the earth's crust are :
Oxygen - 46.6%
Aluminium - 8.1%
calcium-3.63%
gold-0.0011%
But oxygen is a non-metal and aluminium, calcium and gold are metals.
Therefore, Aluminium is the most abundant metal in the earth's crust.
5 of 7 What percentage of a material will persist after 80 minutes if it's half life is 20 minutes?
Answer:
50
Explanation:
What phase change is the following substance undergoing?
First, the particles of this substance are closely packed and
are not easily compressed. After the change, the substance
can flow easily but cannot be easily compressed.
a freezing
b melting
Cevaporation
d deposition
e sublimation
Answer:
b melting
Explanation:
The phase change the substance is undergoing is from solid to liquid and this is called melting.
To understand this process, we need to know the the substance changing. A substance that contains particles that are not easily compressed and packed is a solid. Solids have fixed shapes and volumes. Liquids can easily flow although they cannot also be easily compressed.The phase change from solid to liquid is facilitated by a melting process.
B. Argue: Your classmate predicted the magnets are
going to repel because negative and positive charges
repel each other.
Explain why you agree or disagree. (I agree because
or I disagree because
I
Answer
they atract
Explanation:
True or False, The crust is made up of different plates that can slowly move around?
Answer:
True
Explanation:
There is such thing called tectonic plated
Answer:
True
Explanation:
The crust is made of plates called tectonic plates that move as fast as your finger nails grow, the amount of movement can create both tall and deep earth wonders. Such as the Mariana Trench and Mount Everest. And it causes earthquakes when they slide together.
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In any experiment the accuracy of the data and experiment can be improved. What are some things that can be done to improve data and experiment accuracy?
Choose all that apply:
Conduct more trials.
Add more controls.
Add less controls.
Add more variables
Add less variables
Choose a different person to do the experiment.
Answer:
Conduct more trials.
Add less variables.
Choose a different person
Explanation:
More trials gives plenty of data to be examined.
Less variables makes for less confusion, and less things to keep track of.
Different person ensures that the experiment is not being done by one single person who could be messing up the data
Answer:
conduct more trials, less variables, more controls
Explanation:
more trials make it so if something goes wrong you have other data, less variables because you should only test one variable at a time, more controls helps set your base line for the experiment
