Which of the following equations is balanced correctly? i. 2 ag2o → 4 ag + o2 ii. cu + h2o → cuo + h2 iii. zn + hcl → zncl2 + h2 iv. 2 c4h10 + 13 o2 → 8 co2 + 10 h2o a. ii and iii only b. i, ii, iii, and iv c. ii, iii, and iv only d. i, ii, and iv only

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.

Name two kinds of practical electric pumps.