The atomic number increases moving left to right across a period and subsequently so does the effective nuclear charge. Therefore, moving left to right across a period the nucleus has a greater pull on the outer electrons and the atomic radii decreases.
The answer is C because the weight is going down so they form a gas.
Answer: Streak
Explanation: The color of a mineral in powdered form is called the mineral's streak. To find a mineral's streak, the mineral is rubbed against a piece of unglazed porcelain called a streak plate. The mark left on the streak plate is the streak.
