Well, that depends entirely upon what you are measuring. Grams is a unit of mass and a teaspoon is a unit of volume. For instance: If you fill a teaspoon with water it's weight (mass x gravity) is very small. However, if you fill that same teaspoon with lead it would be much heavier. Seeing that gravity doesn't change, nor does the teaspoon...the only thing that changes is the mass (number of grams). So there isn't a set number of grams per teaspoon. It depends upon what you are measuring. This applies no mater how many Grams or teaspoons you are trying to convert.
4
10
90
2
That is approximately 2.5 teaspoons.
Use a 1/3 teaspoon measuring spoon.
5 grams.
It depends on the size of container you buy. The average size baking powder container sold is 8.1 oz (230g) that size has a little more than 47 teaspoons.
100
20 teaspoons
One tsp of double acting baking powder to one cup of flour.
I wanted to know this for magnesium oxide powder so I did a google search and found two urls which indicated that 1 tsp of baking powder is 5 grams. So, doing the math, and assuming baking powder and ginger powder have roughly the same density, 4 grams would be .8 of a teaspoon! www.joyofbaking.com/bakingsoda.html
3/4 tsp
50
That is approximately 1 teaspoon.