Answer: metals.
Justification:
There are 118 elements which you can find in the periodic table ordered by atomic number. Those elements my be classified into metals, non-metals and metalloids.
The metals are placed on the left side of the periodic table. The metals share the properties of luster, conductivity and flexibility.
The properties of non-metals (which are on the right side of the periodic table) are opposite to those of metals: opaque, low conductivity and brittle.
Metalloids have in between properties.
Copper, for example is a metal: it has luster, is flexible and is highly conductive of the electricity (and temperature).
Answer:
a) 
b) 
Explanation:
Given:
height of water in one arm of the u-tube, 
a)
Gauge pressure at the water-mercury interface,:

we've the density of the water 


b)
Now the same pressure is balanced by the mercury column in the other arm of the tube:



<u>Now the difference in the column is :</u>



Before coming into conclusion first we have to understand both scalar and vector .
A scalar quantity is a physical quantity which has only magnitude for it's complete specification.
A vector quantity is that physical quantity which not only requires magnitude but also possesses direction for it's complete specification.
So the most important factor that differentiate vector from scalar is the direction.
As per the question the student is doing an experiment where he is recording the data obtained during the process.
In order to arrange them in data table, he should ask about the direction of the quantity under consideration.
Hence the correct option is the third option(C)i.e does the measurement include direction?
A force of charge that drive around a circuit is call electeons
Answer:
Explanation:
a ) Momentum of first cart = mass x velocity
= 3 x 4.6 =+13.8 kg m /s
Momentum of second cart = 1.3 x - 1.9 = - 2.47 kg m /s
Total momentum = 13.8 - 2.47
= +11.33 kg m /s
b )
Let the velocity of first cart be v at the moment when second cart was at rest
total momentum = 3 x v + 0 = 3 v
Applying conservation of momentum law
3 v = +11.33
v = +3.77 m /s