random test questions Flashcards
How do continents move? [3 marks]
Tectonic plates are constantly moving under the earth’s crust a few cm every year. Over millions of years, they move thousands of km allowing whole continents to shift apart. This process is called continental drift.
Describe the difference in atomic structure of a hydrogen and helium atom. [3 marks]
A helium atom consists of a nucleus containing two positively charged protons and two neutrons, encircled by two orbiting electrons which carry a negative charge. A hydrogen atom has just one proton and one electron.
Why is neon in the same group in the periodic table as helium? [1 mark]
Elements in the same group have similar chemical properties because the atoms of helium and neon have the same number of electrons in their outer shell.
What has happened to most of the carbon dioxide in the earth’s early atmosphere? [2 marks]
Earth’s early atmosphere was largely made up if nitrogen and carbon dioxide gases. After photosynthesising organisms multiplied on earth, most of the carbon dioxide was replaced with oxygen.
Suggest why most scientists in 1915 could not accept Wegener’s idea of continental drift. [1 mark]
It was difficult to work out how whole continents could move.
Name 2 subatomic particles inside the nucleus of an atom [1 mark]
Protons and neutrons
Why is there overall no electrical charge on each atom? [1 mark]
This is because they contain equal number of positive protons and negative electrons. These opposite charges cancel each other out.
