An effective method of preventing viral diseases in crops is by
Treating the seeds with fungicides
Practicing crop rotation
Regular spraying of crops
Planting resistant varieties
Correct answer is D
No explanation has been provided for this answer.
How many atoms are there in one mole of hydrogen gas? [Avogadro's constant = 6.02 x 1023mol-1]
1.2 x 10 23
6.0 x 10 23
1.2 x10 24
6.0 x 10 24
Correct answer is C
One mole of hydrogen gas has 6.02 x 1023 molecules, and one molecule of hydrogen gas contains 2 atoms of hydrogen
therefore, one mole of hydrogen gas will contain 2 x 6.02 x10^23 atoms
= 1.2 x 10^24 hydrogen atoms
A disadvantage of vegetative propagation is that
Plants are true in type
Fruits are small in size
Plants take a long time to mature
Diseases are easily transferred to offspring
Correct answer is D
No explanation has been provided for this answer.
13.5 g mol-1
18.5 g mol-1
47.4 g mol-1
74.0 g mol-1
Correct answer is D
250cm3 of distilled water contains 14.8g of salt(z)
1cm3 of distilled water will contain \(\frac{14.8 x 1}{250}\) of salt (z)
:. 1000cm3 of distilled water will contain \(\frac{14.8 x 1 x 1000}{250}\) = 59.2g/dm33 = \(\frac{concentration in g/dm3}{molar mass}
0.80 = \(\frac{59.2}{molar mass}\)
molar mass = \(\frac{59.2}{0.80}\) = 74.0 g/mol
Which of the following species does not contain a co-ordinate bond?
AI2CI6
CCI4
H3O+
NH + 4
Correct answer is A
No explanation has been provided for this answer.