General Chemistry Trivia Quiz! Test

Mercury(II)oxide is the correct answer because it is a red solid that decomposes upon heating, releasing oxygen gas. The silvery droplet seen on the cooler parts of the test tube is likely mercury, which is a product of the decomposition reaction. This observation is consistent with the properties of mercury(II)oxide.

Zinc oxide is the correct answer because it exhibits a phenomenon known as thermochromism. When heated, zinc oxide turns yellow due to the movement of electrons within the crystal lattice. As it cools down, the electrons return to their original positions, causing the zinc oxide to turn back to its white color. This property makes zinc oxide suitable for various applications, including as a pigment in paints and as a UV filter in sunscreens.

Ammonium chloride is the correct answer because it fits the description given in the question. Ammonium chloride is a white crystalline solid that sublimes on heating, meaning it changes directly from a solid to a gas without melting. When the gas cools down, it solidifies again on the cooler parts of the test tube, forming the original solid. This process is known as sublimation and is characteristic of ammonium chloride.

Copper (II) carbonate is the correct answer because when heated, it decomposes to form black copper (II) oxide residue and releases carbon dioxide gas, which turns lime water milky due to the formation of calcium carbonate.

Sodium nitrate is the correct answer because it matches all the given observations. Sodium nitrate is a white crystalline solid that melts when heated. When it melts, it gives off a colorless gas that can rekindle a glowing splinter, indicating the presence of oxygen. When a paste of sodium nitrate is mixed with hydrochloric acid (HCl), it produces a golden-yellow flame when held in a non-luminous flame. This is due to the presence of sodium ions in sodium nitrate, which emit a characteristic yellow color when heated.

The given information describes a compound that is a chocolate brown solid, which upon heating gives off a colorless and odorless gas that rekindles a glowing wooden splinter. The residue left behind is reddish-brown when hot and yellow when cold. This behavior is characteristic of lead(IV) oxide.

Lead nitrate is the correct answer because it fits the given description. Lead nitrate is a heavy crystalline solid that decrepitates (breaks down) when heated, leaving behind a reddish-brown residue when hot and a yellow residue when cold. It also gives off a brown gas, which is likely nitrogen dioxide (NO2), along with oxygen.

Ammonium dichromate fits the given description because it is an orange-colored crystalline solid that decomposes upon heating, leaving behind a greenish mass. The decomposition of ammonium dichromate produces nitrogen gas and steam.

Ammonium nitrate is a white crystalline solid that decomposes explosively on heating and leaves behind no residue. One of the gaseous products formed during its decomposition is nitrogen dioxide, which is a supporter of combustion. Therefore, ammonium nitrate is the correct answer.

Ammonium nitrite is the correct answer because it fits the given description. When heated, it decomposes explosively and leaves behind no residue. One of the gaseous products formed is neither combustible nor does it support combustion or turn limewater milky. This matches the properties of ammonium nitrite, making it the most likely compound in this scenario.