CHEMISTRY MIDDLE SCHOOL

Of the following metals, which is the LEAST reactive? A. K
B. Ca
C. Na
D. Mg

Answers

Answer 1
Answer:

Answer: D. Mg

Explanation:

Chemical reactivity is defined as the tendency of an element to loose of gain electrons.

Metals are the elements which lose electrons and hence, their chemical reactivity will be the tendency to lose electrons.

Their chemical reactivity increases as we move top to bottom in a group because the valence shell come gets far away from the nucleus. Thus, the loss of electron from the valence shell becomes easier due to lesser attraction between nucleus and valence electron.

Their chemical reactivity decreases as we move from left to right in a period .As, the electrons get added up in the same shell, the electron in the outermost orbital gets near to the nucleus. And hence, the electron will be difficult to lose.Thus, the chemical reactivity of metals decreases.

For the given options:

Potassium(K) belongs to Group 1 and period 4 of the periodic table.

Calcium (Ca) belongs to Group 2 and period 4 of the periodic table.

Sodium (Na)belongs to Group 1 and Period 3 of the periodic table.

Magnesium (Mg) belongs to Group 2 and Period 3 of the periodic table.

Order of reactivity of metals follow:

K>Ca>Na>Mg

Thus the LEAST reactive metal is Magnesium.
Answer 2
Answer: The Answer Should Be D.Mg

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Which compounds are classified as Arrhenius acids?(1) HCl and NaOH
(2) HNO3 and NaCl
(3) NH3 and H2CO3
(4) HBr and H2SO4

Answers

Answer:The correct answer is option 4.

Explanation:

Arrhenius acids are those compounds which gives H^+ ions when dissolved in their aqueous solution.

HA(aq)\rightarrow H^++A^-

Arrhenius bases are those compounds which gives OH^- ions when dissolved in their aqueous solution.

BOH(aq)\rightarrow OH^-+B^+

HBr \& H_2SO_4 are Arrhenius acids because they form H^+ions in their respective aqueous solution.

HBr(aq)\rightarrow H^++Br^-

H_2SO_4(aq)\rightarrow 2H^++SO_(4)^(2-)

Hence, the correct answer is option 4.
(4) HBr i H2SO4...........

What are the three forms of water and what are the scientific names when they change into each other

Answers

solid liquid and gas

when it changes from a:
solid
  to a
     liquid: melting, fusion
     gas: sublimation
liquid
   to a
       solid:freezing
       gas:vaporization
gas
   to a
       solid:condensation, deposition
       liquid: condensation, liquefacation
gas liquid and solid   gas is when the water evaporates.  liquid when thew water is at room temp and solid when it is cooled below 32 degrees farenheit 

In structure, the standard (Bohr) model of the atom is most similar to A: plum pudding

B: our solar system

C: chocolate chip cookie
dough

D: the Milky Way galaxy

Answers

A. Plum Pudding

This is also a simple google search

What are two cells and how can we tell them apart

Answers

Animal cell- circle, has a larger vacuole
Plant cell- Cell wall, Chloraplast, Rectangle,

5. Enzymes and acidic juices in the stomach, whichbreak proteins down into smaller molecules, is known

Answers

they are known has catalyst.

4. What type of evidence do you think would be most difficult to collect

Answers

Answer:

The type of evidence that is more difficult to collect is evidence known as trace, for example, fibers, hair, or signs of dirt.

Explanation:

For the collection of this type of evidence, specialized equipment such as special vacuum cleaners, tweezers, etc. are used, all with the purpose of carrying out the collection of trace evidence. This type of evidence is characterized by being very difficult to find.

I think it is trace evidence since it is really small and hard to find.
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