'ch' making a 'ck' sound

123456789
Across
  1. 2. When everything is mixed up and nothing makes sense. (5 letters)
  2. 3. Sometimes people have a secret one of these. (6 letters)
  3. 4. If you shout in a cave, you'll hear this. (4 letters)
  4. 7. They sing in harmony, often in a choir. (6 letters)
  5. 8. This keeps a ship steady in the water. (6 letters)
  6. 9. What makes you, you! (9 letters)
Down
  1. 1. This type of knowledge helps you understand how things work. (9 letters)
  2. 2. They mix potions and solutions in a laboratory. (7 letters)
  3. 5. It helps break down what you eat. (7 letters)
  4. 6. The highest ruler in a country. (7 letters)