? asked in 科學及數學化學 · 1 decade ago

chem mc

comparing the element in the secird period the periodic table , from lithium to fluorine ,which of the folloeing sataements is correct?

1. they show a gradual change from gaving metallic property to having

non-metallic property.

2.they show a gradual increase in the number of electron shell in their atom

3.they show a gradual decrese in melting point.

A.1

B.2

C.1,2

D,2,3

when calcium granules are added to water ,colourless gas bubbles are formed.themixture is then filtered to obtain a cleat solution,which of following is correct if excess dil.HCl added to the clear solution?

A.gas bubbles form

B.there is no visible change

C.a white ppt is form

D.the clear solution turn brick red.

2 Answers

Rating
  • Anonymous
    1 decade ago
    Favorite Answer

    1) A

    -statement1 is true(*according to periodic table)

    -statement2 is false(*Li-F is groupI-VII..Group affect the no. of electron only, electron shell is affect by Period1-7.)

    -statement3 is false(*melting point is according to(i)ionic bond (ii)covalent bond (iii)metallic bond)

    2)B

    [eqn:2CaOH(aq)+2HCl→2H2O+CaCl2]

    -A is false(*Ca is belongs to groupII.It mean Ca is alkaline earth metals.If react with acid(HCl)=neutralization=no bubbles)

    -B is true(*CaCl2 is soluble in water.CaCl2 is dissolves in water to give colourless solution.)

    -C is false(*neutralization+CaCl2 is soluble=no ppt.)

    -D is false(*Ca burn in air/water with brick red flame only. )

    Source(s): My knowleedge
  • choy
    Lv 5
    1 decade ago

    1. they show a gradual change from gaving metallic property to having non-metallic property.

    Correct

    2.they show a gradual increase in the number of electron shell in their atom

    Incorrect. They have the same number of shell as they are in the same period.

    3.they show a gradual decrese in melting point.

    Incorrect. There melting points are as follows:

    Li: 453.69K Be: 1560K B: 2349K C: do not melt N: 63.15K

    O: 54.36K F: 53.53K

    A.1 (Answer)

    B.2

    C.1,2

    D,2,3

    when calcium granules are added to water ,colourless gas bubbles are formed.themixture is then filtered to obtain a cleat solution,which of following is correct if excess dil.HCl added to the clear solution?

    Calcium chloride (CaCl2) will be formed. As it is highly soluble in water, no visible will be noted.

    A.gas bubbles form

    B.there is no visible change (Answer)

    C.a white ppt is form

    D.the clear solution turn brick red

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