Diego is performing an experiment using the equipment shown in the diagram. He places filings of zinc metal into a clear colorless mixture of hydrochloric acid and water and then seals the flask with a stopper as shown. He observes that the liquid in the flask bubbles and becomes hot. As time progresses, the zinc metal disappears, and the water level in the cylinder moves down as it fills with gas. Eventually, the bubbles stop forming and the flask contains a colorless liquid, while the cylinder is nearly empty of water. Which of the following would demonstrate a change in properties and disprove Diego’s hypothesis that only a physical change in the water has occurred?

Based on Diego’s experiment, which evidence supports that a chemical reaction has taken place. Note that hydrogen chloride (HCl), which dissolves to produce hydrochloric acid, is a nonflammable gas.

Chlorine bleach and ammonia are two common ingredients in home cleaning products. However, these products should never be mixed together while cleaning, because they can produce dangerous chemicals as a result of their reactions together. One of those reactions involves ammonia and bleach forming the dangerous product chloramine and the harmless product sodium hydroxide. The molecules are pictured here.  In these models, chlorine atoms are medium gray, nitrogen atoms are dark gray, sodium atoms have horizontal bands, oxygen atoms have vertical bands, and hydrogen atoms are light gray.  In this reaction, chloramine is a gas at room temperature. To determine if it follows the law of conservation of mass, the reaction should be carried out in a _____________.

A camper decides to roast a marshmallow. Before roasting the marshmallow, the camper observes that it smells like sugar. After holding the marshmallow over the campfire for 30 seconds, the camper observes that the marshmallow smells like nuts.Which statements explain the marshmallow’s change in smell? Choose the two that best apply.