<span>The answer seems to be: 1.Chemical—triggers release of pancreatic enzyme; Physical—triggers stomach muscle contraction. The second choice is wrong since </span>acetylcholine does not directly influence tongue contraction. The third choice is wrong because of the part "<span>Physical—triggers release of pancreatic enzyme" </span>
Remember, covalent compounds are compounds with bonds between two non-metals. Ionic bonds are those between a metal and a non-metal.
To determine if an element is a metal or non-metal, simply look at the periodic table! So...
a. Li is found on the left side while F is found on the right. A bond between a metal and a non-metal. This is an ionic bond.
b. Mg is found on the left side while S is found on the right. A bond between a metal and a non-metal. This is an ionic bond.
c. This is a tricky one. ammonia, or NH3, is covalent. You just have to remember this one. It has no net charge, unlike its brother NH4 (which has a 1+ charge put is still covalently bonded). Hydrogen has weird properties!
d. Ca is found of the left side while Cl is found on the right. A bond between a metal and a non-metal. This is an ionic bond. Also consider the charges! Ca has a charge of 2+ but Cl only has a charge of 1-. This is why there are 2 Cloride atoms.
120 grams of NaOH means 3 Moles of NaOH because 40 grams (Molecular Weight in grams) is one mole of NaOH.
Each mole of any substance contain Avogadro’s number of molecules ie., 6.022 x (10 to the power 23).
Hence 3 Moles of NaOH contain 3 times of Avogadro’s number of molecules ie., 3 x 6.022 x (10 to the power 23)
Answer:
The Inert Pair effect renders Pb(II) as the more stable oxidation state of lead
Explanation:
SnBr4 + PbBr2 ---> SnBr2 + PbBr4
SnBr2 + PbBr4 ---->
The Inert pair effect is mostly observed between group 15-17 in the periodic table. It leads to stability of the lower oxidation state of an element.
The reason for the Inert pair effect is that the s electrons become Inert due to poor shielding of the d and f-electrons. The Inert pair effect is a tendency of the s electrons not to participate in bonding (remain an Inert pair).
Owing to the Inert pair effect, Pb II is more stable than Pb IV