Answer:
d) cut the large sized Cu solid into smaller sized pieces
Explanation:
The aim of the question is to select the right condition for that would increases the rate of the reaction.
a) use a large sized piece of the solid Cu
This option is wrong. Reducing the surface area decreases the reaction rate.
b) lower the initial temperature below 25 °C for the liquid reactant, HNO3
Hugher temperatures leads to faster reactions hence this option is wrong.
c) use a 0.5 M HNO3 instead of 2.0 M HNO3
Higher concentration leads to increased rate of reaction. Hence this option is wrong.
d) cut the large sized Cu solid into smaller sized pieces
This leads to an increased surface area of the reactants, which leads to an increased rate of the reaction. This is the correct option.
Answer:
The beaker holds 307.94 mL
Explanation:
As we know that the volume that beaker hold is the volume of water that occupied by it.
For this first we have to find mass of the water in the beaker
This can be calculated by the subtraction of beaker's weight from the weight of beaker and water.
weight of water (m) = total weight - weight of beaker
Empty weight of beaker = 25.91 g
Weight of beaker with water = 333.85 g
Weight of water = 333.85 - 25.91 = 307.94 g
Density of water = 1 g/mL
We have
Mass = Volume x density
307.94 = Volume x 1
Volume = 307.94 mL
The beaker holds 307.94 mL
The answer is: the distance between two nuclei is 2.35×10⁻¹⁰ m.
r(Na⁺) = 1.16×10⁻¹⁰ m; radius of sodium cation.
r(F⁻) = 1.9×10⁻¹⁰ m; radius of fluoride anion.
d(NaF) = r(Na⁺) + r(F⁻).
d(NaF) = 1.16×10⁻¹⁰ m + 1.9×10⁻¹⁰ m.
d(NaF) = 2.35×10⁻¹⁰ m; distance between two nuclei.
The sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
Physical chemistry is the area that deals with the
mechanisms, the rate, and the energy transfer that occurs when matter undergoes
a change. So the correct option for the given question is option “B”. Whenever
there is a change in the state of matter, the physical properties definitely
undergo a change. A solid matter will always have a definite shape and volume,
while a liquid has a definite volume but no shape. Gases do not have either definite
volume or shape. Chemical properties might not be affected, but physical
properties are definitely impacted when a matter undergoes change.
Answer: The correct answer is a) Acetylcholine.
Explanation:
The acetylcholine is a very important neurotransmitter involved in the mediation of synaptic activity between neurons. Among its most important functions we find: expression of mood states, vasodilation, gastrointestinal motility, bronchoconstriction, circular iris muscle contraction and sweat gland secretion.
Therefore the correct answer is a) Acetylcholine.
