Question

increases strength but may cause brittleness
a. carbon
b. manganese
improves corrosion resistance
c. chromium
d. nickel
adds toughness, especially in cold
improves weld flow and toughness

Explanation:

Carbon in metals increases strength but can lead to brittleness. Chromium improves corrosion - resistance. Nickel adds toughness especially in cold conditions and also improves weld flow and toughness.

Answer:

increases strength but may cause brittleness - a. carbon
improves corrosion resistance - c. chromium
adds toughness, especially in cold - d. nickel
improves weld flow and toughness - d. nickel