4.0 g of sodium hydroxide in 250 cm3 of solution contains?
0.40 moles per dm3
0.10 moles per dm3
0.04 moles per dm3
0.02 moles per dm3
Correct answer is A
Unit of concentration = (moles)/(dm3)
If 250 cm3 solution NaOH contains 4.0 g NaOH
i.e -1cm3 solution NaOH (4.0)/(250) g
∴ 1000 cm3 (1 dm3) will contain (40 x 1000) / (250 x 1) = 16 g/dm3
16 g/dm3 = 16g/dm3 + molar mass NaOH
because no of moles = (mass of substance given) / (molar mass)
∴ (16 g) / (40 g) dm3 = (16 g)/(dm3 x (1 mole)/ (40g) = 0.4 (moles)/(dm3)
NH3 + H3O+
→ NH4+ + H2O. It may be deduced from the reaction above that?
a redox reaction has occurred
H3O+ acts as an oxidizing agent
H3O+ acts as an acid
water acts as an acid
Correct answer is C
No explanation has been provided for this answer.
pH values are equal
HCI solution has a higher pH
sum of the values is 14
ethanoic acid solution has a higher pH
Correct answer is D
No explanation has been provided for this answer.
deliquescene
hygroscopy
effervescence
efflorescence
Correct answer is D
No explanation has been provided for this answer.
Water can be identified by the use of?
anhydrous copper (II) tetraoxosulphate (VI)
anhydrous sodium trioxocarbonate (IV)
potassium heptaoxochromate (VII)
copper (II) trioxocaronate (IV)
Correct answer is A
Anhydrous CuSO4 will turn blue with water