Answer:
Option B is correct.
4
Explanation:
We know that an atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.
All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example, if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.
In given problem we are given with 2 neutrons of helium. We know that the atomic number of He is 2. Thus Mass number of He is,
Number of neutrons + number of proton
2 + 2 = 4
Thus, option B is correct.
Answer:
750mmHg
Explanation:
The following data were obtained from the question:
T1 = 127°C = 127 +273 = 400K
T2 = 27°C = 27 +273 = 300K
P1 = 1000mmHg
P2 =?
P1/T1 = P2/T2
1000/400 = P2 /300
Cross multiply
400 x P2 = 1000 x 300
Divide both side by 400
P2 = (1000 x 300)/400
P2 = 750mmHg
Therefore, the new pressure after cooling is 750mmHg
d. Fe(s) and Al(s)
<h3>Further explanation</h3>
In the redox reaction, it is also known
Reducing agents are substances that experience oxidation
Oxidizing agents are substances that experience reduction
The metal activity series is expressed in voltaic series
<em>Li-K-Ba-Ca-Na-Mg-Al-Mn- (H2O) -Zn-Cr-Fe-Cd-Co-Ni-Sn-Pb- (H) -Cu-Hg-Ag-Pt-Au </em>
The more to the left, the metal is more reactive (easily release electrons) and the stronger reducing agent
The more to the right, the metal is less reactive (harder to release electrons) and the stronger oxidizing agent
So that the metal located on the left can push the metal on the right in the redox reaction
The electrodes which are easier to reduce than hydrogen (H), have E cells = +
The electrodes which are easier to oxidize than hydrogen have a sign E cell = -
So the above metals or metal ions will reduce Pb²⁺ (aq) will be located to the left of the Pb in the voltaic series or which have a more negative E cell value (greater reduction power)
The metal : d. Fe(s) and Al(s)
Answer: Tall fescue can be harmful to grazing cattle and horses because the grass can become tough and infected with endophytes, causing poor grazing. Switchgrass and tall fescue are less likely to be poisonous to dogs, cats or humans than to horses or cattle, but eating either of them might cause stomach upset.
Explanation:
Chemical
bonds between atoms in reactants undergo change during a chemical
reaction.
<span>The substance (or substances) initially involved in a </span>chemical reaction<span> <span>are
called reactants or reagents. </span></span>Chemical reactions<span> <span>are
usually characterized by a </span></span>chemical<span> change,
and they yield one or more products, which usually have properties different
from the reactants.</span>
The correct answer between all
the choices given is the last choice or letter D. I am hoping that this answer
has satisfied your query and it will be able to help you in your endeavor, and
if you would like, feel free to ask another question.
