Answer:
continental-continental convergent boundary
Explanation:
When two continental plates converge, they smash together and create mountains. The amazing Himalaya Mountains are the result of this type of convergent plate boundary. The Appalachian Mountains resulted from ancient convergence when Pangaea came together.

Blank # 1 - keep safe distance from the burner
Blank # 2 - Place the equipments on the right place after use
Blank # 3 - perform experiments with proper lab equipment and safety tools
Blank # 4 - Don't break any test tube or lab equipment
(maybe it can be hazardous)
Antoine Henri Becquerel discovered radioactivity when he was studying
X- rays.
He had been studying phosphorescent uranium ores and hypothesized that they might absorb sunlight and reemit it as X-rays.
His hypothesis was wrong, but his experiments led to the discovery of <em>natural radioactivity</em>.
H2S and HS- are a conjugate acid-base pair.