X509Certificate2 certificate = <Some Certificate>

bool isCertificateValid = certificate.Verify();

X509Chain chain = new X509Chain();
chain.Build(certificate);
chain.ChainPolicy.RevocationMode = X509RevocationMode.Online;

if ((chain != null) && (chain.ChainElements != null) && (chain.ChainElements.Count > 0))
{
    foreach (X509ChainElement element in chain.ChainElements)
    {
        sb.AppendLine("Имя сертификата: " + element.Certificate.GetNameInfo(X509NameType.SimpleName, false));
        sb.AppendLine("Сертификат валиден: " + (element.Certificate.Verify() ? "да" : "нет"));

        foreach (X509ChainStatus status in element.ChainElementStatus)
        {
            sb.AppendLine(status.Status.ToString() + ": " + status.StatusInformation);
        }
    }
}