تحدي chemistry

Which of the following elements have the same group reagent of calcium ion?

• Cl₁₆

• Hg₈₀

• Kr₃₆

• Sr₃₈

When an end of platinum rod covered with the powder of compound (x) is approached to Bunsen flame as the figure illustrated the non-illuminant region in the flame acquires brick red color, when the solution of compound (x) is added to sodium carbonate solution, a white precipitate is formed. What is compound (x)?

• Aluminum chloride

• Calcium nitrate

• Cupper (II) sulphate

• Magnesium sulfate

Consider the following statements.

(A) The highest and most common oxidation state of Group 8 shown in their oxides than fluorides.

(B) Fe can exist in the form of +2.

(C) Mn, Cu, Hg easily form M(II) compounds.

Which statement(s) is/are correct?

• None of the above

• B and C

• A and C

• A and B

Which of the following couldn’t be oxidized?

• FeO

• Cr₂O₃

• K₂MnO₄

• K₂Cr₂O₇

If (n) is order of a main transition series, so the outermost sublevel that is successively filled is……………………..

• (n+4) d

• (n+3) d

• (n-2) d

• (n+2) d

(X&Y) are two successive elements from first transition elements, if element Y is the last element that can lose all of 4s and 3d electrons, so ionization potential of X that’s can break completely filled level of noble gas is…………………..

• 10th

• 7th

• 8th

• 9th

Consider the following statements.

(A)The highest and most common oxidation state of Group 8 shown in their oxides than fluorides.

(B)Fe can exist in the form of +2.

(C)Mn, Cu, Hg easily form M(II) compounds.

Which statement(s) is/are correct?

• None of the above

• B and C

• A and C

• A and B

The pH of a solution of a strong acid is 5.0. What will be the pH of the solution obtained after diluting the given solution 100 times?

• 7

•  7.5

• 6.6

• 5.9

To obtain a red orange fumes which can turns a paper wet by starch into yellow we can use an oxidizing agent. Then that reagent is added into cation X to give a white ppt.

So the salt might be…………………

• FeCl₂

• FeBr₃

• AlI₃

• CaBr₂

The equations of the production of iron in the blast furnace are given. Answer the following questions.

(1) C+O2 →CO2

(2) CO2 +C→2CO

(3) CaCO3→CaO+CO

(4) 2CaO+SiO2 →CaSiO3

(5) Fe2O3 +3CO→2Fe+3CO2

Which substance reduces hematite in the metallurgy of iron?

• SiO₂

• C

• CO2

• CO