1 Which of the following is an essential element in plants?A) Nitrogen B) Nickel C) Aluminum D) Lead 2 Choose the correct order of soil horizons in a soil profile, starting from surface level.A) Leaching zone, living organisms and humus, weathered rock, subsoil B) Humus, weathered rock, leaching zone C) Weathered rock, subsoil, topsoil D) Topsoil, subsoil, weathered rock 3 A soil with mostly _____ particles has large spaces and the water drains right through them.A) silt B) sand C) clay 4 The final decomposition of organic remains in humus to inorganic nutrients is performed by _____.A) microorganisms B) earthworms C) small plants D) insects 5 Which of the following is a micronutrient?A) Iron B) Potassium C) Carbon D) Calcium