Grade 5 Science Practice Test: Mixtures, Solutions and the Particle Model

Dissolving splits the sugar into particles too small to see, and they spread out among the water particles. The sugar is still there: the water tastes sweet and the mass is unchanged.

Mass is conserved when a substance dissolves, so 200 g + 20 g = 220 g. Choosing 200 g assumes the dissolved salt no longer counts.

Iron is attracted to a magnet, while sand is not. Salt, sugar, flour, pebbles and sand are not magnetic.

Sand grains are too large to pass through filter paper, but water passes through. Sand is not magnetic, and stirring or adding water does not separate anything.

When the water evaporates, the dissolved salt is left behind as crystals. Filtering does not work because dissolved salt particles pass through the paper with the water.

Gas particles are tiny and always moving. Adding more of them means more collisions with the inside of the ball, so it feels firm; the particles themselves do not get bigger.

Melting is a change of state, and no matter enters or leaves the sealed bag, so the mass stays the same. Liquid water is not lighter than the ice it came from.

Bubbles that appear when two substances are mixed are evidence that a new substance has formed; here it is carbon dioxide gas. Nothing is heated, so it is not evaporation or melting.

Particles in a solid stay in fixed positions but still vibrate. Sliding past each other describes a liquid, and moving freely far apart describes a gas.

In a solution one substance dissolves evenly into another and you cannot see the separate parts. Sand settles, oil floats on vinegar, and nuts and raisins can be picked apart.