Which of these pairs of elements have the same number of valence electrons?

phosphorus (P) and chlorine (Cl)

berylium (Be) and calcium (Ca)

chlorine (Cl) and helium (He)

oxygen (O) and carbon (C)

For the reaction N₂ (g) + 3H₂ (g) ⇌ 2NH₃ (g) what is the value of Kc at 500 ∘C if the equilibrium concentrations are as follows: [H₂] = 0.50 M, [N₂] = 0.50 M, and [NH₃] = 2.1 M? Express the equilibrium constant to two significant figures.

Identify the Brønsted-Lowry acid, the Brønsted-Lowry base, the conjugate acid, and the conjugate base in each reaction: (a) (CH3) 3N (aq) + H2O (l) ⇌ (CH3) 3NH + (aq) + OH - (aq) (b) HNO3 (aq) + H2O (l) ⇌H3O + (aq) + NO3 - (aq) Drag the appropriate

You are given a liquid. Briefly describe the steps you would take to show whether it is a pure substance or a homogeneous mixture.

Which type of radioactive product has zero mass and zero charge?

A sample of 0.53 g of carbon dioxide was obtained by heating 1.31 g of calcium carbonate. what is the percent yield for this reaction? caco3 (s) ⟶ cao (s) + co2 (s)

Which of the following transitions would release energy? n=2->n=3 n=1 - > n=3 n=3 - >n=1 n=3->n=2

Which animal group actually saw a drop in the number of endangered and threatened species between 1995 and 2005? a Fish b. Reptiles c. Birds d. Mammals

Why does burning fossil fuels put ecosystems under pressure?

What is the quantum number set of the ground-state electron that is found in helium (He) but not in hydrogen (H) ? (1, 0, 0, - ½) (1, 0, 1, - ½) (1, 1, 0, - ½) (1, 1, 1, - ½)

What must be true in order for magnetism to induce an electric current in a wire? There needs to be a switch in the circuit. There cannot be a switch in the circuit. The wire must be part of a closed circuit. The wire must be part of an open circuit.