Finely ground sugar is Castor sugar also called superfine sugar. Icing sugar is also a very finely ground sugar
One tsp is 5gm. 40gm of castor sugar is approximately 8 tsp.
Castor sugar.
Dissolving will depend on surface area. Castor sugar has a smaller particle than regular sugar. The smaller the particle the larger the surface area. Surface area: Regular sugar < castor sugar < icing sugar. Castor sugar should dissolve faster than the same mass of regular sugar but slower than the same mass of icing sugar.
Castor (or caster) sugar is a type of British fine sugar. It is called castor because its grains are small enough to pass through a sugar caster (sprinkler).
Caster sugar has finer granules than regular (or "granulated") sugar. For cupcakes, you should be able to use regular sugar instead of castor without any detriment to the final product.
granulated sugar means less fine sugar. fine sugar is the same as castor sugar!
Flour is more of a powder and is easily compressed. Varying density means varying amounts of flour. As I understand it, sifting flour is done to slightly aerate the flour to give it a consistent density. A consistent density is favorable to accurate measurements being obtained when baking, since recipes call for specific amounts of ingredients for them to work. Sifting also removes lumps. Sugar, the basic processed granules you buy to bake with, is all of a consistent size. Sifting would tend to break up the granules into smaller pieces. This would make the sugar more dense and could throw off measurements as well as affect taste. Powdered sugar tastes different and acts slightly different than granule sugar. For these reason, sifting would not be recommended for sugar, though if it clumps, banging it around a bit to bust up the clumps should be fine.
8 ounces
It is 2 tablespoons.
That is 0.772 cup.
Castor sugar, it is finer than regular sugar and dissolves faster.