In the Rutherford scattering experiment, a beam of alpha particles was fired at a thin gold film and few of…

Step 1: Analyze the question Alpha particles were fired at a very thin gold foil. Most passed straight through, but a few were deflected through large angles (some even bounced back). We need to find what this tells us about the nucleus.

Step 2: The concept Rutherford's observations and what each one means:

• Most particles passed straight through. Most of the atom is empty space.
• A few were deflected considerably. Alpha particles are positively charged, so only a strong positive charge can repel them strongly. The charge must be concentrated in a very small region. If the positive charge were spread out through the atom, as in Thomson's "plum pudding" model, no large deflections would occur.
• Very few bounced straight back. The nucleus is extremely small and dense (a tiny volume holding most of the atom's mass).

Step 3: Evaluate the options

• A. Positively charged and concentrated in a tiny volume. Correct. Large deflections come from repulsion between the positive alpha particles and a small, dense, positive nucleus.
• B. Contains protons and electrons. Wrong. The experiment says nothing about electrons being in the nucleus, and they are not.
• C. Contains alpha particles. Wrong. The nucleus contains protons and neutrons. The alpha particles came from the source.
• D. Distributed in a tiny volume and emits alpha particles. Wrong. "Distributed" contradicts the idea of concentration, and the gold nucleus did not emit the alpha particles.

Step 4: Answer The correct option is A.

Tip: Remember the Rutherford summary as "Most through, few deflected, very few back". This gives "empty space, small positive nucleus, dense nucleus". Whenever you see "deflected considerably," think "positive and concentrated."