Answer:
D) The given reaction is Exothermic, because energy is released
Explanation:
Here, given that Zinc is added to a beaker containing hydrochloric acid.
Also, the beaker gets warm.
⇒The energy is released in the form of heat.
EXOTHERMIC reactions are those type of reactions in which energy is released in the form of heat.
When the beaker gets warm, the reaction is exothermic in nature.
Hence, the given reaction is Exothermic, because energy is released
Answer:

Explanation:
Given:
width of the wire, 
thickness of the flat wire, 
length of the wire, 
voltage across the wire, 
current through the wire, 
Now the net resistance of the wire:
using ohm's law



We have the relation between the resistivity and the resistance as:

where:
a = cross sectional area of the wire
resistivity of the wire material


Answer:20
Explanation: i konw this stuff
(C)
Explanation:
The circle has a radius r = 0.5 m, which means that its circumference C is

One revolution means that the stopper travels a distance equal to the circumference of the circle so the velocity of the stopper is

The force of gravity between the astronauts is 
Explanation:
The magnitude of the gravitational force between two objects is given by:
where
:
is the gravitational constant
are the masses of the two objects
r is the separation between them
In this problem, we have two astronauts, whose masses are:

While the separation between the astronauts is
r = 2 m
Substituting into the equation, we can find the gravitational force between the two astronauts:

Learn more about gravitational force:
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