1/D

2/B

3/A

4/D

5/D

6/D

7/A

8/D

9/C

10/C

11/B

12/D

13/B

14/A

15/B

16/C

17/D

18/

19/B

20/A

21/C

22/D

23/A

24/C

25/C

$PTPƯ:Na_2O+H_2O\xrightarrow{} 2NaOH$

$n_{Na_2O}=\dfrac{6,2}{62}=0,1mol.$

$Theo$ $pt:$ $n_{NaOH}=2n_{Na_2O}=0,2mol.$

$⇒CM_{NaOH}=\dfrac{0,2}{2}=0,1M.$

26/D

$PTPƯ:K_2O+H_2O\xrightarrow{} 2KOH$

$n_{K_2O}=\dfrac{9,4}{94}=0,1mol.$

$Theo$ $pt:$ $n_{KOH}=2n_{K_2O}=0,2mol.$

$⇒CM_{KOH}=\dfrac{0,2}{0,1}=2M.$

27/C

28/A

$PTPƯ:H_2O+CaO\xrightarrow{} Ca(OH)_2$

$Ca(OH)_2$ là bazơ làm quỳ tím chuyển màu xanh.

29/A

30/C

$PTPƯ:2C_2H_2+5O_2\xrightarrow{t^o} 4CO_2+2H_2O$

$n_{C_2H_2}=\dfrac{6,72}{22,4}=0,3mol.$

$Theo$ $pt:$ $n_{O_2}=\dfrac{5}{2}n_{C_2H_2}=0,75mol.$

$⇒V_{O_2}=0,75.22,4=16,8l.$

chúc bạn học tốt!

1D 2D 3A 4D 5D 6D 7A 8D 9C 10C 11B 12D 13B 14A 15A 16C 17D 18B 19B 20A 21C 22D 23A 24C 25A 26C 27C 28A 29A 30C