Critical Thinking: A neutral sodium atom loses one electron. What happens to the atom?

Researchers test a light therapy device for fatigue. Participants assigned to the device are told that they are receiving the active treatment, while the comparison group receives no device. Fatigue is measured by self-report. Which change would best reduce expectation effects?

A balance gives 25.80 g, 25.79 g, and 25.81 g for an object whose certified mass is 25.00 g. Which action would most directly improve the validity of future measurements?

A research team wants to study whether long-term air pollution exposure is associated with development of asthma. Deliberately assigning people to high pollution exposure would be unethical. Which design would provide the strongest feasible evidence among the choices below?

A runner begins treating severe ankle pain on the day it reaches its worst level. She starts rest, compression, an over-the-counter pain reliever, and an herbal balm at the same time. A teammate says the same balm cured his ankle pain. The runner expects the expensive balm to work and searches only for positive reviews after she begins feeling better. Which sources of potentially misleading evidence are present? Select all that apply.

A thermometer is placed four times in a 37.0 C calibration bath and reads 39.1, 39.1, 39.2, and 39.1 C. Complete the evaluation: The thermometer has [1] because its repeated measurements are consistent, but it has [2] because the readings are far from the accepted value.

Which option correctly matches each biological macromolecule with its primary building block or major components?

Hydrogen bonds between water molecules contribute to several important properties of water. Which is one example?

A Fahrenheit thermometer registers 80 degrees F outside. What would a Celsius thermometer read?

Select each of the following personal items that a student can have on the laboratory bench during the experiment.