Answer:
True
Explanation:
According to Aufbau's principle "sublevels with lower energies are filled up before those with higher energies".
Sublevels do not fill up in numerical order but there is a certain manner in which they are filled. The pattern is shown below:
1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p e.t.c
We see that the 4s gets filled before the 3d sublevel.
Answer: The correct answer is option B.
Explanation: There are 7 elements in group VIII-A. They are Helium (He), Neon(Ne), Argon(Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) and Ununoctium (Uuo). They are considered as a part of group 18.
Metals are shown in purple color in the periodic table. Metalloids as blue color and Non-metals are shown in green color.
Group VIII-A elements have fully filled orbitals and hence are most stable amongst all the elements in the periodic table. They are considered as least reactive elements and as they are categorized as non-metals. So, they are the least reactive non-metals.
Therefore, the correct option is B.
Answer:
Substitution.
Explanation:
Claisen reaction was first published in 1887 by a prominent German chemist known as Rainer Ludwig Claisen.
A Claisen reaction is a nucleophilic substitution in which an enolate is the nucleophile. It's typically a reaction of two molecules of an ester to form a β-keto ester, in the presence of an alkoxide base. Thus, a Claisen reaction is simply a characteristic condensation reaction of esters through a nucleophilic carbonyl substitution with an enolate such as a ketone enolate or an ester enolate.
Furthermore, a Claisen reaction results in the formation of a carbon-carbon bond in the presence of a strong base to yield a β-keto ester.
Answer:
The reaction vessel will feel cool
Explanation:
In an endothermic reaction, heat is absorbed by the reaction system from the surrounding. The withdrawal of heat from the surrounding causes the reaction vessel to feel cool.
Hence when an endothermic reaction is going on, the reaction vessel feels cool when touched.
<span><span />It is water’s Ionization Property. Water
Ionization also known as self-ionization or auto ionization of water creates a
positive and Negative ion which is essential for chemical reactions. It is a
reaction of pure water in where a water molecule and H2O combined to make a
hydroxide ion. It usually occurs due to the electric field fluctuation between
2 neighbouring molecules. It is a property of pure water that mixed or
dissociates to from a new substance which is a hydrogen ion (positive ion) and
hydroxide ions (negative ion)</span>
