Each unit of electricity costs 0.8$, how much does it cost to run a 500W appliance for 4 hours?​

What is hidden during a lunar eclipse? isn't the moon hidden?

In which situation has the independent variable for the experiment been changed? check all that apply. changed from counting the number of duckweed at day 0 and day 14 to counting them every day changed from testing duckweed growth in beakers to testing duckweed growth in large outdoor tanks changed from testing the effect of ph on duckweed growth to testing the effect of light levels on duckweed growth changed from testing the effect of acid ph on duckweed growth to testing the effect of basic ph on duckweed growth

Work out sian speed for the first 30 minutes of her journey. give your answer in km/h.