RICHMOND, Va. (AP) – Legislation that would exempt certain chemicals used in hydraulic fracturing from public disclosure is advancing in the Virginia General Assembly.The House gave preliminary approval Monday to Del. Roxann Robinson’s bill that would exempt information about chemicals deemed a trade secret from the Virginia Freedom of Information Act.Robinson, a Republican, said the bill is necessary to protect the oil and gas industry and its closely held trade secrets.But opponents say the bill would keep landowners in the dark about pollutants that might be affecting their groundwater.Fracking involves pumping water, sand and chemicals underground to split open rock formations and allow oil and gas to flow.