Answer:
a solution color becoming less intense due to dilution- is not an evidence of a chemical reaction
bubbles (gas formation) - evidence of a chemical reaction
explosion or fire - evidence of a chemical reaction
changes in color- evidence of a chemical reaction
precipitation- evidence of a chemical reaction
changes in temperature - evidence of a chemical reaction
a solid liquifying - is not an evidence of a chemical reaction
solution colors mixing - is not an evidence of a chemical reaction
Explanation:
A chemical change is not easily reversible and yields new substances. It is often accompanied by a loss or gain of heat.
In the answer section, i have shown some evidences that lead us to conclude that a chemical reaction has taken place. The occurrence of a chemical change often goes with the formation of new substances as earlier stated and any of these signs may accompany the process.
For instance, when a metal is dropped in dilute acid solution, bubble of hydrogen gas indicates that a chemical reaction has taken place.
Explanation:
Sodium has 1 electron in its outermost shell, and chlorine has 7 electrons. It is easiest for sodium to lose its electron and form a +1 ion, and for chlorine to gain an electron, forming a -1 ion.
<em>Now ionic bonds areIons are formed by atoms that have non-full outermost electron shells in order to become more like the noble gases in Group 8 of the Periodic Table,</em>
<em>Now ionic bonds areIons are formed by atoms that have non-full outermost electron shells in order to become more like the noble gases in Group 8 of the Periodic Table,Some atoms add electrons to get a full shell, thus becoming a negative ion. Other atoms subtract electrons from their outermost shell, leaving a full </em><em>shell and an overall positive charge..</em>
<em>shell and an overall positive charge..therefore it is an</em> ionic bond
As the temperature increases, B) the molecules started moving faster.
Explanation:
The temperature of a substance is a measure of the average kinetic energy of the particles in a substance. In particular, it can be found that the temperature is directly proportional to the average kinetic energy of the particles:
The kinetic energy of a particle is given by
where
m is the mass of the particle
v is its speed
This means that the higher the temperature of a substance, the greater the speed of the particles in the substance.
Therefore, if we apply this concept to this problem, we infer that as the temperature of the water in the pond gets higher, the speed of the molecules inside the water increases, which means that the molecules are moving faster.
Therefore, the correct answer is
B) the molecules started moving faster.
Learn more about temperature:
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Remember that a cation will be smaller than its neutral atom, and an anion will be larger than its neutral atom. This would automatically eliminate answer choices A and D.
Also keep in mind that atomic radii decreases from left to right as you move along a periodic table. It also decreases from bottom up.
Atomic radii increases as you move from right to left and as you go from up to down.
As bromine is higher up in the periodic table than Iodine, it would have a smaller radius. Iodine would have a larger radius.
The correct answer is B. Br
Answer:
0.75 cal/g°c
Explanation:
for specific heat we have formula:
Amount of heat absorbed or released = mass x specific heat of a substance x change in temperature.
ΔQ=m x c x ΔT
where c= specific heat
m= mass of a substance
ΔT = total temperature
ΔQ = Amount of heat
so for specific heat,
c= ΔQ/mxΔT
c= 280/25x (25-10)
c= 280/375
c= 0.75 cal/g°c
