When two surfaces slide against each other, a force called friction makes them stick very slightly together. Smooth surfaces, like ice and glass, are easy to slide over. They create very little friction. Rough surfaces like rock and sand create much more friction, and are easy to grip on to.
hope it helps...!!! 
 
        
             
        
        
        
<span>...a concordant intrusion.
In geology, "concordant" means the same as "sill" -- or, an intrusion that has gotten in between older layers of rock (or even beds of volcanic lava). An intrusion with boundaries parallel to layering in surrounding rocks suggests this, meaning it is considered to be a concordant intrusion.</span>
        
             
        
        
        
<h2>Answer:</h2>
<u>A) Increase the voltage by adding a bigger battery </u>
<h2>Explanation:</h2>
According to Ohm's law 
V = IR
where V is voltage, I is current and R is the resistance. If we write the equation for resistance we would get
R= V / I
Here we can see that Voltage is directly proportional to Resistance so in order to keep the balance if we increase the resistance then we must increase the voltage to keep the current constant.
 
        
        
        
Answer:
I would say both 
Explanation:
Each silicon atom has four valence electrons which are shared, forming covalent bonds with the four surrounding Si atoms. 
Carbon contains four electrons in its outer shell. Therefore, it can form four covalent bonds with other atoms or molecules. The simplest organic carbon molecule is methane (CH4), in which four hydrogen atoms bind to a carbon atom (Figure 1).