Answer:
Conduction directly affects air temperature only a few centimeters into the atmosphere. During the day, sunlight heats the ground, which in turn heats the air directly above it via conduction. At night, the ground cools and the heat flows from the warmer air directly above to the cooler ground via conduction.
Explanation:
This question is testing to see how well you understand the "half-life" of radioactive elements, and how well you can manipulate and dance around them. This is not an easy question.
The idea is that the "half-life" is a certain amount of time. It's the time it takes for 'half' of the atoms in any sample of that particular unstable element to 'decay' ... their nuclei die, fall apart, and turn into nuclei of other elements.
Look over the table. There are 4,500 atoms of this radioactive substance when the time is 12,000 seconds, and there are 2,250 atoms of it left when the time is ' y ' seconds. Gosh ... 2,250 is exactly half of 4,500 ! So the length of time from 12,000 seconds until ' y ' is the half life of this substance ! But how can we find the length of the half-life ? ? ?
Maybe we can figure it out from other information in the table !
Here's what I found:
Do you see the time when there were 3,600 atoms of it ?
That's 20,000 seconds.
... After one half-life, there were 1,800 atoms left.
... After another half-life, there were 900 atoms left.
... After another half-life, there were 450 atoms left.
==> 450 is in the table ! That's at 95,000 seconds.
So the length of time from 20,000 seconds until 95,000 seconds
is three half-lifes.
The length of time is (95,000 - 20,000) = 75,000 sec
3 half lifes = 75,000 sec
Divide each side by 3 : 1 half life = 25,000 seconds
There it is ! THAT's the number we need. We can answer the question now.
==> 2,250 atoms is half of 4,500 atoms.
==> ' y ' is one half-life later than 12,000 seconds
==> ' y ' = 12,000 + 25,000
y = 37,000 seconds .
Check:
Look how nicely 37,000sec fits in between 20,000 and 60,000 in the table.
As I said earlier, this is not the simplest half-life problem I've seen.
You really have to know what you're doing on this one. You can't
bluff through it.
Hey there mate ;), Im Benjemin and lets solve your question.
★ (Alkanes) : forms single bonds between carbon atoms.
The first four elements are gases and others are liquid in state.
★(Alkenes) : forms double bonds between carbon atoms.
The first three alkenes are gases and rest are liquid.
★ (Alkynes) : forms triple bonds between carbon atoms.
First three are gases and the last one is liquid.
According to boiling point :
The larger structure of the hydrocarbons, the higher the boiling points they have.
In the 3 tables, we can see that the boiling point increases.
Answer:
C.Melt both cubes and look for a broader range of melting temperatures. The one that melts over a broader range of temperatures is the amorphous solid.
Explanation:
Amorphous solids is one that do not have a fixed melting points but melt over a wide range of temperature due to the irregular shape hence its name. Contrariwise crystalline solids, have a fixed and sharp melting point.
This comes in handy to solve the riddle. We can characterise the pair with the melting point property.
Answer:
K^+ and NO3^-
Explanation:
In a balanced ionic equation, we usually see the species that react to yield the main product in the reaction.
Consider the reaction;
Pb(NO3)2(aq) +2 KI(aq) -------> PbI2(s) + 2KNO3(aq)
The main product in this reaction is PbI2. Hence the balanced ionic equation is;
Pb^2+(aq) + 2I^-(aq) ------> PbI2(s)
Notice that K^+ and NO3^- did not participate in this reaction. All ions that are part of the molecular equation but do not participate in the ionic reaction equation are called spectator ions. Hence K^+ and NO3^- are spectator ions in this reaction as can be seen clearly above.
